OPTION 1
x3 Sonos Play 1 would be an awful lot easier, then for the main room you use, look add an additional Play 1 so you can have 2 as a a stereo pair. They sound fantastic and easily fill our 7x6m open plan kitchen/living area. Not the bassiest, but impressive for their size and work well for a party.
Total = £510
Simple, sound good, plug and play and can be added to for stereo pairs (forget about Play 3 or 5).
OPTION 2
Otherwise you'd have to:
- x3 Chromecast Audio - £75
- x3 2ch amps (ONEU/LEPY on rainforest) - £65
- x3 pairs e-audio 6.5" ceiling speakers - £105
- Speaker cable (say sommer meridian) - £50
TOTAL = £295
CCAs are good, amps should be ok, but all would need a power socket each (6 total), a cluster**** of wiring. The ceiling speakers are likely average unless you spend decent money (£200/pair) on decent ones.
OPTION 3
Replace the amps and ceiling speakers for desktop speakers (meh for positioning/mounting).
Conclusion
Just go for Sonos unless you want to spend out on expensive wall mounted or ceiling speakers, then have to mess around running wires and trying to control the amps or powered speakers themselves. You'll easily spend a grand trying to implement a decent in-ceiling solution.
Personally:
I'm considering phasing out the Sonos Play 1 pair and adding the Chromecast Audios (x5) I have in storage as a house multiroom system, as we have most things already in place:
Lounge - CCA -> HiFi/AV Setup.
Kitchen/Living - CCA -> Arcam Soundbar & Sub (to buy).
Front Office - CCA -> BOSE Soundlink.
Main Bedroom - CCA to Portable Bluetooth Speaker (with Aux in, to buy).
Hall - N/A as can be heard from Kitchen/Living & Office
Portable/Patio - CCA to Portable IPX7 Bluetooth Speaker (with Aux in, to buy).
Sonos Play 1s could be sold to fund the Arcam Soundbar, then just need to grab the portable bluetooth speakers, like JBL Charge, Riva S, Anker Soundcore etc.