​​​​Although not ideal, the speakers placed at different heights should sound ok. Be sure to perform Trueplay tuning.

The Era 300s are not designed to be your primary TV speakers. And if you connect the TV to the Era 300’s line-in port, you will likely experience lip sync issues.

Okay that’s great. Thanks.  I’m still thinking about how to set things up but the room is a bit awkward. I might have to get mor speakers. Cheers. 

@Saybadger 

I really won‘t recommend using speakers of a stereo setup on different hights. Just my own experiences…

And besides the analogue input is no good idea for tv sound as of the told reasons, you also won‘t be able to use just one of a stereo setup for that. I think for your corner tv position a soundbar like for example the Sonos beam might be a good solution.

Regarding to your Era stereo setup there of course are possibilities to mount them on a nearly same hight. Wall mounts… floor stands… or even some diy solutions.

Sure. Thanks. That’s helpful. I might need to go with a sound bar for the TV. 
 

I'm getting rid of my separates. Are these speakers decent in stereo or do people just buy one generally?

Read the Era 300 page and pay attention to the mounting suggestions versus your space. If they don’t match up a pair of Fives are much more forgiving on mounting locations and likely would sound better.

Put a soundbar under the TV, an Arc if possible but a Beam or Ray aren’t bad choices.

https://www.sonos.com/en-us/guides/era300

Select a location

Trueplay tuning will adjust the sound for wherever you place Era 300, but for the speaker to project sound most effectively, here are a few guidelines:

• Era 300 should be placed indoors and have approximately 2' (.61m) of overhead clearance for optimal sound quality. Placement in an enclosed space like a bookshelf is not recommended as this could impact dispersion and playback clarity.
• If you are mounting Era 300 within 2' (.61m) of a ceiling, place it upside down for the best sound.
• When Era 300 is placed next to a wall or on a shelf, leave at least 1" (2.5cm) clearance in back and 8” (20.32cm) on each side of the speaker.
• <snipped surround info>
• Traditional stereo setups often have an ideal place to sit in a room for the best listening experience, but with Era 300 the sound is sent in all directions so you'll experience rich detail no matter where you’re seated.
  
  Note: Don’t position Era 300 vertically or at a steep angle or the audio will stop.

Thanks for the advice. I am quite tempted by the 5 but two of them is a lot of money. 

I use 2 5s plus a sub gen 2 for music listening streaming plus vinyl and the 5 is best for stereo listening 

unless you are looking for atmos music that is

Not as good as the Fives (In my pretty weak opinion**) but you could get a pair of Era 100s and a Sub-Mini for $887 versus the Fives at $1048. The set is hidden under “Home Theater Completion Set” way down the Sonos shop’s page.

** If my hearing test last week didn’t show 50 to 70 dB hearing loss I’d trust my ears more. Listening tests for me now really come down to my hearing aids opinion.

Depends on your claims… and your room situation. If there’s the possibility of placing the speakers well, I always would prefer a stereo pair. But the Era300 are engineered for Atmos music… so I would take them, if Atmos music is a must have feature. And as @Stanley_4 said that also brings the additional requirements with it. 
So without the need of Atmos music (which at the moment is just available on Sonos with Apple music and Amazon music) a pair of Sonos Five or (less expensive) Era100 might be a better choice. 

$900 for two Era 300’s isn’t small change either…

Yes. I’m in UK where two 300s is about £790 and two 5s is £1k. So yes, neither is cheap. 

I haven’t heard Atmos. I’m not really into it in principle but I am going to need to go and have a listen I think, to see if it’s any good. 

Try smart home sounds 

https://www.smarthomesounds.co.uk/2-x-sonos-five-bundle

call them ask if you can get a discount code plus you get a 6 year warranty 

also they have great service 

it also depends on what streaming service you use I use Qobuz which has not got atmos which suits me as I tried it and it didn’t impress me

good luck choosing