What hotel are you staying at?
I found that if you stay anywhere close to downtown, you are going to have to pay 20 something or more a day for parking.
Also, as an outsider coming to the city, I found (if you are interested in the history) the Heinz History Center
to be a GREAT introduction to the area. It'll take you about 2-3 hours to walk through the whole thing if you are just perusing. Some of it is quite interesting.
Also, after going to Primanti's a couple of times, I found that my wife and I like Peppy's as much or more. It also is in the strip district... which MUST be done on a Saturday morning.... I see most people here kinda skipped over the district itself. I think many of the "natives" don't realize just how unique it is... as it is right in their backyard. make SURE you spend a couple hours just walking through the strip district. Go into all the little ethnic grocery stores. Check out the sports stuff on the sidewalks and take note of how all different ethnicities are playing the same song! It, in a nutshell, well tell you everything you need to know about Pittsburgh, IMO... (hey locals...am I wrong here?)
Enjoy the trip... I sure am jealous!