I’m also open to any other design / system component ideas everyone has. I have experience in audio/video but it certainly isn’t my profession. 

For the Amps, I wouldn’t use a network closet.  Wire the speakers to the wall where the TV is and put the two Amps there.  Connect one to HDMI-ARC on the TV and use the other as surrounds.  Connect the Sub wirelessly.  

I think you are overcomplicating things, and increasing your cost, and getting a worse audio experience by using only ceiling speakers with an end run to a central location.  A huge part of the reason Sonos exists is so that you do not need to go this route.

Stereo audio is best when it’s at ear level, not coming from the ceiling.  If you’re talking about audio from a TV, the audio should becom ing from near the screen, again, not from above.  Of course, that’s not ideal aesthetically in a cases, so compromised are sometimes made.  Likewise, some rooms, like a bathroom or kitchen, you don’t have a distinct listening area to point to, so ceiling speakers are as good as any other option.

In short, I would look at replacing many of those ceiling speakers with Sonos wireless speakers instead.

As far as distributed video goes, Sonos amp and soundbars are looking for and HDMI-ARC signal, which is not the same as normal HDMI audio.  The idea is that HDMI sends audio to your TV, and then the TV sends audio to your sound system via HDMI-ARC.  There are exceptions, but just keeping it simple.  So what you really want is to just distribute the video to each TV, then have each TV distribute the audio to the local sound system.  With Sonos, that could be a soundbar, amp mounted behind the TV, or amp in a closet somewhere in the house. 

I have somewhat of a distributed video system  with 4 TVs. I have a few source sin a closet, along with appropriate HDMI matrix and splitters.  One TV is main, with a Sonos Arc connected to it, a second TV is nearby and always plays the same source with no audio.  Other 2 TVs are outside, each with a Sonos amp connected to them sitting in the master bedroom closet (they could be in the main closet with all the other gear, but not worth the effort to migrate it).  The HDMI cable between TV and Amp is around 30 feet with no issues.

Thank you for the feedback! 

Based on your suggestions I have redesigned the speakers and layout a little bit to get your opinions. 

Also, I’m curious if it would be better to do TV mounted soundbars on both outside TVs. (these TVs will be on full motion mounts to swing towards the open area of the deck where the furniture will be) But it makes me question how the video distribution would be without using an HDMI Splitter for the outdoor area. The idea is for both TVs to play the same content without any lag or delay, audio or video, between them. The only way I know how to ensure this is possible would be to use a splitter and a single input source delivered to both TVs. One would think if you delivered the same content to both they wouldn’t have any lag between them, but every TV processes audio at a different rate and I’m concerned the audio would be off between the two if I were to use soundbars connected to the ARC of the TV directly, thoughts? 

Relatively short, different audio and video delays are only significant if you can view and/or listen to multiple screens from a given position.

In Zone2 each room should have an individual Volume control. For the two single speaker rooms, use specialized speakers that connect to both channels, but there is only one hole. As far as AMP is concerned, it will be driving three pairs of stereo speakers.

At 75’ you are getting into the big leagues with HDMI. This can be done, but not casually. Assume that the HDMI cable will fail at some point in the future and use a routing scheme that will allow replacing the cable without a lot of fuss.

If you don’t want to place AMP(s) in the same room as the TV’s, I suggest that you consider something other than SONOS.

Consider two or three pairs of speakers in the garage.

Also keep in mind that the speed of sound is rather pokey at about one foot per millisecond. Consider three listeners and two speakers (connected to the same source) on opposite sides of a 30 foot room. Listener ‘A’ standing by speaker ‘A’ will claim speaker ‘B’ is 30ms late. Listener ‘B’ will claim ‘A’ is late while listener ‘C’, at the midpoint, will claim that the speakers are synchronized. All observers are correct.

In Zone 6 viewers/listeners will be able to see both TVs simultaneously and the plan is for both TVs to play the same content. This is why I’m concerned about any lag. In the other zones it’s not as much of a concern like you stated, it’s unlikely anyone would notice when moving from one room into another. 

I do plan to utilize stereo speakers in the rooms containing only one speaker and volume controls in sub zones, good call. 
 

I agree completely on the length limitations for HDMI. I was hoping that using an extender would eliminate these concerns though? 

At 75’ you’ll be using an active cable. You’ll have some trouble finding HDMI-eARC cables at 75’. Don’t be cheap. A couple years ago they didn’t exist, but there are now some HDMI over CAT-6 extenders. I’m not aware of any HDMI-eARC over CAT-6 extenders.

If you use a 1-2 HDMI splitter at the source and connect SONOS to each TV you won’t have any sync issues -- unless one of the TV’s introduces something.

A 1-2 HDMI-ARC switch does not make any sense. (that’s why there are none) If you want to keep all the AMP’s in the closet, you’ll need to use something like an ARCANA on each HDMI switch output in order to generate the eARC channel. And you’d need to wire all of the AMP’s to the network.

This gets more complicated if you sometimes want to run separate programs to each TV. 

Yes, bars can run multiple sources to dozens of screens and the TV’s stay synchronized. They don’t use SONOS. While not cheap, it’s amazingly simple at only one “box” per device. (and a very robust local network) Unfortunately, this is not currently a DOLBY ATMOS compatible scheme.