Sonos is primarily a multi-system music serving system, offering multiple products from servers, to server/amps, to speakers, to all in ones. Ease and flexibility is their niche. BlueSound (fathered by NAD) is a late comer with similar offerings at lower prices but higher quality.
I enjoy my $100 Logitech UE Smart Radio. It's basically a wireless clock radio with a 6 hour battery built in. Has 12,000 streaming sources built-in and can access any music stored on computers connected to your wireless network. It's small, has pleasant monophonic (woofer/tweeter) sound that makes for great background listening. Meant to stay within range of your wireless network.
(No point in trying to do stereo with a 15 inch spread.)