I don't even know what I want! I DO know my wife wants a simple interface

The TiVo box IS also the cable box. In order for it to work with the Cable provider, one installs a "Multicast cable card" into the TiVo and registers it with (in my case) Comcast. After that, Comcast pushes some code to it that enables the TiVo to decode the subscribed premium channels and Xfinity instant streaming stuff. So, the unfiltered r/f content is split and directed to the coax inputs of the cable modem and of the TiVo box.

Thanks, jgatie, I'd completely forgotten about that. Wow. Haven't seen that movie in about 20 years :)

Probably because of the pain caused to that Ferrari at the end of the movie.

As the OP, I'd like to thank everyone who contributed and gave me an immersive introduction to a product line that's likely to join all the Apple stuff that litters my house within the next year or two. However, what I've realized by asking all my questions (and learning from your so-considerate answers) is that my most acute problem is what happens when there's no place to sit on our couch that's littered with remotes that my spouse sometimes comes close to throwing at me. This problem didn't exist until I redirected the viper's nest of cables lying behind my credenza in hopes of making use of the 4K capability of my television set. For the moment, that's limited more by the availability of content than by the equipment I have to watch (and listen) to it.

I've spent about $600 on it already (two new TiVos, a 4K Blu Ray player, a few "specimen" DVDs, and the result is 5.1 sound that I THINK now works better and the aforementioned remote disaster. The latter is my most critical problem. The thread title brings me back to reality. What I really need right now is for my spouse to be able to come in to the house after a hard day at work, sit down, and listen to the music she wants or watch the video she wants without needing two extra pairs of hands to juggle the remotes. You Tube, Kickstarter, and Magnolia/BestBuy tell me there are many "solutions" to this problem that offer to increase my investment and my wife's frustration but more likely worsen her frustration (Savant, NEEO, and SevenHugs, I'm talking about YOU) at a cost that can't currently be measured.

I've never taken on the challenge of programming a Logitech Harmony Remote, but at least I know who they are, and can see from amazon reviews that they have a fairly positive following. So, first things first: get my existing devices to work together by clicking on or talking to ONE magic wand, and THEN I can work on piping Mahler, David Bromberg, Les Mis, and Chris Botti throughout the house and outside to the barbecue (after all, my spouse is a vegetarian) via a growing ecosystem of Sonos products.

Thanks for putting up with all my questions; I'll continue hanging out here, because there seem to be nice people here paying attention to the stuff I'll be lusting after--oops, I meant improving my life with 🆒

I've found that the Harmony programming interface is pretty easy for basic operations, but has the complexity available for when you want to get into the minutiae. I tend not to do that, ever. But I do love my Harmony Elite. The hardest part wasn't the programming, it was figuring out where to put the little infrared sensors so they'd be seen by all of my devices 🙂

Just ordered the Harmony Elite from amazon. Great package pricing available at Best Buy if you want to be seduced into the Alexa or Google ecosystems, but I'm a stubborn Apple guy (long ago Apple had a smart marketing guy named Guy Kawasaki working for them--believe it or not, he came to them from the jewelry marketing business!; his business card listed his job title as "Evangelist." His motto then was "Cut me: I bleed 6 colors").

Of course, today that would be Jony Ive, saying "Cut me: I bleed a barely discernible monochrome gray."

amazon prime delivery being what it is, I think my tomorrow is already scheduled for me 😃

I'm going to start by laying out what I think would be an ideal setup for you (if you go the Sonos route, that is) and then will dig into some of the specifics of the questions you've laid out.

Audio: Sonos Playbar, 2 Play:1 surrounds and a Sub. There is no way to mix additional speakers into the Sonos Playbar setup (i.e. front right and left). The Playbar itself is designed to cover front left/center/right and that can't be changed. By all means, buy some and use them in different rooms as part of a whole-home audio setup, but that will be the only use for them.

Receiver/Switch: For HDMI-equipped sources a simple 4K-compatible multi-input HDMI switch (not a full blown receiver) with a single HDMI running from that to an input on the TV. For non-HDMI sources (like the VCR), run it straight to the TV, which I'd imagine at least has a dongle for connecting legacy equipment. One wrinkle here that I'll get to below is that you may need an HDMI switch with an optical output as well.

Remote: Logitech Harmony Elite or Harmony Companion. I prefer the simplicity of the Companion, but the Elite is a bit more full-featured and has a screen that may make trouble-shooting and other tasks more straight forward.

Now, on to some of your questions and concerns. I don't know how to parse out different quotes in a reply, so apologies if this is a little hard to follow.

"Will my devices lose their 5.1 surround sound on their voyage from source to Sonos? (I'm confused about whether to blame the TV or Sonos for this)"
Blame both. Sonos elected to use what many would consider to be a legacy connector/input (optical) to make setup simpler and less intrusive. This cable can't carry certain 5.1 signals (Dolby Digital Plus, DTS...), meaning you just can't get 5.1 from sources that only output in that format. By doing this, they also rely on the idea that you'll have a TV which passes 5.1 signals untouched from HDMI sources plugged into inputs out of the TV's optical out. Some do. Many don't, and you can fault the TV for that. Key is to triple check whether or not yours will do this. If not, there are workarounds involving HDMI switches with optical outs or stand-alone optical switches, but these setups will be significantly more complicated. Hopefully, your TV does and it'll be a moot point. If you find out it doesn't, happy to give some more detailed guidance on how to get around that.

"Will I be able (occasionally) to stream BlueTooth from my iPhone to the Sonos System? (I've paid Apple a LOT for all those Mahler Symphonies sitting in uncompressed format on my iPhone)."
You will not be able to do this over Bluetooth from your phone's native apps (Sonos doesn't have Bluetooth). You will be able to access your phone's music library (and your computer's music library) through the Sonos app. Short of it is that you'll have to learn how to do it a little differently, but it'll work. You mentioned being able to use headphones in a subsequent post. I believe the answer is no, but will let others offer guidance.

"Am I absolutely nuts to think that anyone can really make that Savant remote, with its huge majority of pejorative reviews, work? (Most of those reviews say that it's REALLY seductive, but then develops all kinds of problems actually fulfilling its promises). I'm not really anticipating knowledgeable input about that specific remote here, but perhaps some pointers towards single-remote peace in the home."
Have zero experience with or even knowledge of the Savant remote and don't particularly care to have either. A properly setup Logitech Harmony will work perfectly for what you want. The setup process has a learning curve and you may want to find someone to pay to do it, but the experience is absolutely seamless and there are even built-in troubleshooting functions if something somehow gets screwy.

"Is there some other way to get a "single remote" experience (same question)"
See above.

"What about HDR video? I think my current LG TV and 4K BluRay player support HD10, but for future-proofing, if I'm spending all this money I'd like to know that when I get my 4K HDR OLED TV that supports DolbyVision I'll be able to see and hear the benefits of that purchase"
Make sure that you get an HDMI switch that supports passthrough of 4K and HDR and you should be fine. The switch won't give you any better features/compatibility, but it's important to make sure you don't get one that will just pass signals untouched and not "stand in the way" of your TV using its own technology.

"How will I incorporate my legacy equipment (my wife again, wanting to watch those ancient VHS tapes, and me, wanting to plug in my 4K capable 2016 MacBook Pro, assuming I assemble the right "dongles" to do so). If someone chimes in with knowledge/guesses/wild speculation about whether Apple AirPlay might one day accomplish that I'd be grateful and not hold you to it"
Plug MacBook Pro in via HDMI to either the switch or a TV input. Already covered the VCR connection.

"Probably the same question: how will I get enough HDMI inputs? Do I need a receiver in here somewhere? Would the Sonos "Connect" have a role in this?"
Connect has no role in this. Get a switch with as many inputs as you need - there are lots of options out there and many people on here with experience using them.

"Although the remote can label a source as "VCR", the Bose console has no analog video inputs to make use of that label (I suspect there are precious few VHS VCRs blessed with digital outputs)"
Whereas most Harmony activities you set up will just change the input on the HDMI switch and keep it on the same TV input (that the switch is plugged into), here you'll set up an activity or two that changes the TV input to the analog one. Sound is routed out of the TV to the Playbar over optical, so no need to worry about getting audio from these to the Playbar some other way.

On to your (and many other people's) concerns about getting 5.1 to the Playbar, here's a quick summary. Before that, though, I want to point out that you should not get yourself worked up about this if you don't think you'll really notice or be bothered by a lack of real 5.1 surround sound. The Playbar creates its own simulated surround off of stereo signals (as many soundbars do) and many users find it adequate, though you'll see that the more relatively vocal users on here tend not to. Just a little disclaimer as this topic can take you down a rabbit hole into a world of multiple switches, new bluray players, ARC, etc. and you may just not need to go there.

As you've read, most TVs will output 5.1 sound over optical, but only from their built-in tuners and streaming apps - not useful if you're using all external sources.

If your TV doesn't pass 5.1, you need to find another way to get sound directly from your devices to the Playbar without having to go through the TV. This is where HDMI switches with optical out come into play. You run everything via HDMI into the switch, then one HDMI to the TV and one optical to the Playbar.

Two issues here. First is that you're going to have legacy equipment plugged directly into the TV's analog inputs so you'll need to find a way to get sound from there to the Playbar. Optical out from TV to a separate optical switch sitting between HDMI switch and Playbar - more complex setup and operation and far from ideal. Second is that any devices that output in Dolby Digital Plus (which is the norm for many streaming boxes) will only get you stereo sound because DD+ cannot travel over optical and thus will "stop" when the device recognizes that it's supposed to send audio over the switch's optical output.

Now, let's assume that your new(ish) LG TV is similar to my new(ish) LG TV and that it will pass 5.1 signals untouched and will also transcode (convert) DD+ to standard DD, which can be sent over optical. This would mean that as long as DD or DD+ 5.1 signals make it to your TV over HDMI, they will make it to your Playbar.

The remaining issue is DTS. I know little about Bluray audio formats as I don't even have a player, but this is the most popular among them. Whether or not it will even travel on an optical cable (I forget if it will or not), the Playbar is not equipped to decode it. So, unless your Bluray player can transcode "on the fly" from DTS to DD (some definitely can), you won't be able to get surround from it (only stereo). Purists will tell you that transcoding isn't a solution because it diminishes the uncompressed quality of the native audio. I say if you're looking to simplify in a Sonos-type system, you may just have to accept that you're going to cut a corner here and there and DD 5.1 instead of DTS isn't the end of the world.

I'm going to stop here and let you get back to me with questions.

Wow! Someone who can stand my verbosity and respond in kind (albeit with information instead of rambling questions!). Thank you SO MUCH.

My move to Sonos has been postponed (or perhaps interrupted) by my realization that my most pressing problem is appeasing my spouse's understandable frustration at the machinations she must go through just to turn on the TV.After reading just horrible reviews of the (very seductive) Savant remote and watching even MORE seductive Kickstarter and You Tube videos covering others that aren't even marketed products yet but promise to scratch my back, make my coffee, and choose my clothing for me (OK, they don't promise that, but one does say that if I wave it at the window it will open the drapes), I've decided to sit out a few innings before making big purchases and instead try to create a bit of calm at home by buying the Harmony Elite remote.

I suspect I may end up with Sonos eventually unless Bose comes to its senses, and perhaps during the next year or two the acronym wars regarding surround sound, HDR video, and even voice control via Google, amazon, and Apple will modulate a bit. Firmware updates for Bose products are arcane. Firmware updates for Sonos seem sometimes to cause as many problems as they solve. Meanwhile, I can watch TV, get 4K video from my TV, and listen to my music from my iPhone, my wife's record player, Spotify,Pandora, and others. Maybe by the time I'm ready for whole house wireless audio, Sonos will have upped their game and more seamlessly support current surround sound standards (that DOES seem to be the market they're trying hardest to capture, although now that I look, I see their single speakers on display at my personal shopper's temple (the Apple Retail Store).

Thanks again!

The only time I can remember gaining this much learning from someone whose name was all in base 10, it was 24601, singing while pulling on a rope while being whipped by Javert

(Columbo raincoat on)
May I ask just one more question?
Bose includes a faux headset (it actually contains microphones) with its systems that it claims enables their setup firmware to "tune" its systems to the ambient environment. I've seen allusions to something similar existing for Sonos. Do you think they work? (opinions, summaries of others' opinions, or URLs all equally welcome)

Thanks again!

Happy to help out. Went through several fits and starts myself with how to get everything working so figure it's worth sharing some of the knowledge and experience built up over that period.

Those tuning systems are pretty common among AV receivers too and (I think) are meant mostly to automate the process of setting speaker distances and speaker/sub crossover frequencies. Sonos does have a relatively new function like that which uses your phone's mic and a few circles around the room while waving it to optimize a speaker for the size and layout of the room it's in. No clue how it actually works or what adjustments are really made, but I know people on here have found it to yield better sound generally.

Note that when User385289 says "phone", (s)he really means iPhone. Or, more technically, any iOS device that has a microphone. Sonos hasn't yet been able to do it for Android powered devices, due to the varied nature of the microphones in them. Apple is much more "standard" in their requirements.

I have used TruePlay(Sonos' version of the modification of speakers) on all my speakers. For me, it's a slight improvement, but others have reported extreme changes. I suspect it depends on where the speakers are placed, and how well your ears work.