I looked at Sonos..but it is proprietary, and their speakers are good, not great.
What seems to work for me is simply AirPlay, but with some caveats.
I store all of my best music (Apple Lossless encoded) on a Mac Mini, that is connected by HDMI to my Arcam receiver and 5 Epos speakers. I run iTunes as the main playback mechanism in my lounge via this, and it doubles to play video off my NAS (the NAS also backs up the Mac Mini to guard my music collection - and the NAS backs up to Glacier). I then have an Airport connected to a Creek integrated amp and more Epos 12.2 speakers in the kitchen, and a Denon Picollo AirPlay receiver in the bedroom connected to a pair of Monitor Audio Vectras.
I control it all via my Android phone, using "Remote for iTunes" app from the Play store, or using my iPad. I can even remote login to the Mac Mini from my MacBook and control it.
Because it is AirPlay, and Spotify knows about AirPlay, my gf (who is a Spotify lover) can connect to most of the speakers with AirPlay from her MacBook - but not the Arcam in the lounge, as that isn't an AirPlay receiver (yet).
Quality is pretty good, latency is manageable, and because AirPlay is a standard I can buy more extension speakers of whatever quality I want/can afford to expand. My gf is in love with the B&O AirPlay portable speaker, so we may need one before summer for the garden. Or something much cheaper as my bank details dictate.
N.B. - I bought a used set of Epos 12.2s for the kitchen off eBay, because I love the ones in the lounge. The seller had just gone to Sonos, and as he put it, it was a downgrade...