Best Multi Room AV Set Up?

Not a cheap option but this sounds like a perfect fit for a Sonos system. I have been running one for a few years and you can do everything you need.

I have Sonos One in bedroom and kitchen, and a pair in the office to give stereo sound. (alternatively you could go for the larger Five but honestly, a pair of Ones sounds incredible and is more than enough - or the Ikea Symfonisks are cheaper and basically the same unit (less voice control) and completely compatible)

Then in lounge I have a Beam soundbar connected to the TV with two Ones for surround (again, alternatives available being the Arc which is bigger/supports more features but for my needs the Beam is plenty; again Symfonisks could be used instead)

Any ceiling speakers can be included by connecting to a Sonos Amp.

You can play music in any room, all rooms, or a group of rooms - all are synced perfectly so as you move between rooms there is no noticeable difference. You can stream from Spotify straight to any speaker or group (although, you can't stream different things from the same spotify account to different rooms at the same time which I think is a spotify limitation - although maybe that is different if you had a family subscription). You can also stream your own library from a NAS drive or computer. or if you are watching TV again you can stream the audio to any or all speakers.