@Shaq64 

The Sonos amp, with two or 4 speakers, always is a ONE room configuration. So you select ONE specific audio source and all speakers connect to the amp are playing the same audio. 
If you like to play some different audio on the single ceiling speaker that’s NOT possible with one amp. 
If a group of your surround setup together with an amp for the ceiling speakers fits your taste for music, is a very personal decision. 

Thanks very much for your answer! That makes sense…

And about the 1st question, what would you recommend? Would that make sense to add ceiling speakers in addition to surrounds speakers?

The ceiling speakers cannot be incorporated into the surrounds.  The best you could do would be to group them with the surround room.  However, this would result in a 75 ms delay for the Amp for TV sources, and the Amp would be playing all 5.1.2 channels downmixed to stereo, which would basically ruin the surround effects.  Not really recommended. 

Great stuff!! Thanks very much for your recommendation! Much appreciated

You’d not gain a lot from the ceiling speakers, maybe actually end up worse depending on their quality.

They might be nice to have as background music but buying an Amp is an expensive option compared to just switching your Surrounds to Full Mode for music playback.

@Shaq64 

In the end imo it really depends on the ceiling soeakers quality. If they are high end speakers, a Sonos amp might be worth it. 
But as you said… using them for music should be the plan. There’s no sense using them in addition to tv sound. 

@Schlumpf 

I really don't think they are high end ceiling speakers so I will avoid wasting my money on an amp and stick to my current set up!

Thanks for all the answers