I know the Pirates suck, but you have to go to PNC Park.  I've been to 5 major league parks (Minute Maid Park, Coors Field, Kauffman Stadium, Old Busch Stadium, and PNC Park), and PNC Park is the best.  The atmosphere and the food are great, and they have Primanti Bros. there by the way.  I've had one of those sandwiches with the fries on it, and it's great.

The one other place I suggest you try is a place called Fatheads.  The food is nothing special, but they are noted for having a huge, and apparently ever changing, selection of beer on tap.  I'm not a big drinker at all, but I do like this place.  They will give you small samples on the beers to taste, so be sure to taste a few before you order.

http://www.fatheads.com