I agree with gatchel. After crunching the numbers, you can get 4 audio zones with 2 wireless controllers for $2000 with Sonos (compare this to other multi-zone systems that are not so plug-and-play). If you have an existing amplifier, you can get a ZP90 (line-out only) or, if you have an area in need of amplification a ZP120 provides speaker level out. It can play all of your stored music files and also supports line-in audio from "old school" technology. The system is plug-and-play and always works. Aside from the wireless controllers, you can control the system from a PC with the included software. Plus you can link zones at will with complete synchronization.
Keep in mind, Sonos is meant to be a distributed system and not centralized. If you need to centralize your ZonePlayers due to pre-existing wiring, a ZoneBridge can be added to allow the wireless controllers to maintain a connection to the the ZonePlayers on the fringe of their wireless range. My system is currently centralized and instead of a ZoneBridge, I have integrated the Sonos system into my HA application to allow distributed control. Using a program called HouseBot, I am able to control all of my ZonePlayers functions (browsing available music, building a queue, transport control, display album art, etc.), though control of music services (Rhapsody, Pandora, etc.) is not exposed. Music services could be added in the future...but I just don't use them so there isn't a huge impetus for me to reverse-engineer and add the code.
My approach to HA was to add media first...primarily audio. Sonos was the most robust system when I purchased about 2 years ago and it remains so today. Tapping into the system for external control was not that difficult and I see Sonos as being a big player in distributed audio into the future.
Osler