My oldest Daughter goes to Pitt. For your initial visit the best bet would be to listen to buffetbuster. The places he mentions should be part of the campus tour.
The only place that I would add is Enrico’s (not biscotti) in Shadyside if you want a nice sit down dinner and a good glass of wine. Everything is cooked in a wood burning oven. Their motto is "no freezer, no fryer, no microwave".
Speaking of wine, The Union Grill on Craig Street. They only mark-up their wine $4-$6.00 per bottle. Great food and lots of it at a cheap price. A student favorite.
Then there is the Fuel & Fuddle on Oakland Ave. Excellent bar food. I believe the food is all 1/2 price after 11:00 PM.
I’ll stop now. This just happens to be one of my favorite subjects.