Thanks for the responses!
iTunes....My wife just ditched her iPod for a Zune HD. She just hated the PC software and ultimately could never get it to sync properly with consistancy(double playlists, etc. and all kinds of little annoying things.) I tunes installed on a windows PC with multiple user accounts has also caused issues... I'm a fairly technical guy..and to be honest, I just got tired of always "straightening it out" for her.
So honestly...with no iPods (or iPhones or iPads) in the house, I just did not want iTunes installed and possibly messing up her music collection that was just re-organized, straightened out and now syncing nicely with her Zune exactly they way she wants.
Now...if I can install I-tunes software and not have it *touch* (modify) her library other than to just play-back music I may consider AirPort as an option. Is that possible...or will it attempt to re-organize her library, etc.
Sonos does look pretty much like exactly what I'm looking for...though of course pricey. (Isn't that always the way...)
In comparing the two (functionality wise):
AirPort is by default limited to playback only through iTunes...so streaming other internet content (Pandora, LastFM, Zune Marketplace) is not supported. Then again it looks like 3rd party programs like AirFoil circumvent this...which assuming it works as advertised would allow me to stream any content that my PC can "play" to airport stations.
Sonos natively supports popular internet radio (like Pandora, LastFM) but does not support Zune Marketplace streaming (which my Wife has not subscribed to yet, but is considering now that she owns a Zune), but with the Zune plugged into a Sonos Player, that would enable songs to stream from Zune Marketplace through the house.
I have not seen an "airfoil equivalent" type program available for Sonos, though you could connect the line-out of a streaming PC to the line-in of a sonos player.
In addition to having an iPhone app, Sonos also has proprietary controller ans is also bringing out an Android based app. (Of course...in my house we currently only have Blackberries and soon maybe a Windows 7 phone for my son...)
So in the end I think I have themajor pros / cons of AirPort vs. Sonos:
Airport: lower implementation cost, ability to stream anything from a PC assuming AirFoil 3rd party app works as advertised. I should be able to expect to stream to about 4 stations via wireless. ITunes needs to be installed (may or may not be an issue).
Sonos: More control options. Ability to connect any device as an audio-in to a Sonos Player and stream throughout the hosue. (So each "room" is not only audio-out, but can serve as audio-in). Should be able to stream simultaneously to many more zones vs. airport.