- can't say this enough: Cat5e or cat6 (or fiber, I guess) everywhere. It's worth futureproofing.
+1 more on that. It's not just for networking - there are so many signals that can be converted to go over CAT cabling you really are leaving your future options open. Also, this will serve your daughter well if you go with the more 'off the shelf' solution like Sonos or Squeezebox to name a couple. Hardwired is always better than wireless if you have a choice.
Personally I have the Sonos system and can recommend it highly - it easily does both individual audio in each room or spreads a single source through all zones - you really get the best of both worlds.
