Well, kind of an open ended question, but I'll jump in. I use a sonos for both critical listening as well as causal listening and now that I do I would never go back to my previous configuration (a bunch of airport express/airTunes speaker sets)--
For critical listening I listen to my Apple Lossless music through an outboard DA Converter. For more casual/friends over in front of the fireplace I usually put on Rhapsody or Pandora (both relatively inexpensive add-ons which give you unlimited access to music you don't own.
Everyone loves taking a turn with the sonos handheld controller and selecting songs, and it is now my teenage daughter's favorite gadget (of which I have many)--go for it!
Mark