I live in Pittsburgh. Right around the corner from your hotel is a great Indian restaurant called India Garden...it is one of my favorite places in the entire city. They have a great buffet.
http://www.indiagarden.net/ Mad Mex is also not far from your hotel, it is mexican food, but not your typical mexican food - it is a local Pittsburgh chain.
http://www.madmex.com/oakland/
If you want something a little more fancy, Legume is a great restaurant within walking distance.
http://www.legumebistro.com/ It has a little bar/lounge next door called Butterjoint that I would be comfortable taking my kids (5 and 10) into.
http://thebutterjoint.com/
Pamela's for breakfast.
Not sure that I would recommend it, but the "O" or the "Dirty O" as Pitt Students call it, is the Original Hot Dog Shop. It is a late night Pitt institution...and you might want to stop in just to say you have been there.
All of the restaurants I recommended are within walking distance of your hotel.
Someone else recommended the South Side. I would avoid the South Side on Saturday night with a high school student....it is primarily focused on drinking and if your DD goes to school in Pittsburgh, she'll have more than enough time to find it. They have been cracking down on just about everything there and the police presence is heavy.
I would second the recommendations to visit Phipps Conservatory.
Shadyside has some cute boutique shops that you could visit, but you would need to drive there (the shuttle may possibly go there, but I can't say for sure as I've never used it). If you do go there, try Prantl's bakery and the little crepes place that is in a basement.