First, let me say that SONOS is hands-down the best, most flexible and affordable multi-room music system out there. Don't hesitate to invest in the SONOS system as its easy to set up, operate and manage, and the materials and build quality are right up there with Apple and Bose.
The only decision I think you'll need to make is whether you want the Play:3 or Play:5. We have a number of both in our system, and the sound from the Play:5s are noticeably better -- fuller, richer and rounder. By comparison the Play:3 sounds good, performing well with music and radio, but is less rich than the Play:5s. While the Play:3 looks smaller than the Play:5, its deeper design means that in my experience the Play:3 takes up the same space as the Play:5... and in some cases more space, because the less-deep Play:5s often fit better onto ledges and bookshelves.
In summary, if this is your first audio output for your SONOS system, go for the Play:5. If you're adding a player to your existing system for a smaller room (kitchen, bathroom), low-occupancy area (hallway) or where absolute sound quality matters less (you listen only to the radio in your bedroom in the mornings) then go for the Play:3.