The Advice I Was Looking For
Thanks for the great answer. The Squeezebox sounds like a great product but I think the convenience of the Sonos is going to win the day. It is reassuring to hear positive reports on its audio quality from people running FLAC files. I can't wait to complete our addition in November and get one of these systems up and running. The one other system that could snag me is the Olive Musica, which also has the ability to stream around the house like the Sonos. The single Musica costs more than the Sonos bundle, but Olive's room-extension modules (Sonatas) are only $199 and look sorta like on-wall iPods, which can be operated manually or via remote. So that's appealing, but there are some unpleasant postings around about Olive products, and the Sonos meanwhile seems to elicit positive vibrations all around. Also, with the Olive, it just seems like you're locking into a lot of hardware (a 160GB HD on board the unit at $1099 total, or 250GB for $1500), whereas the Sonos is more modular and therefore flexible down the road.
Glad to hear you really like yours.
Austinbirdman