I grew up in the Pittsburgh subs, so I thought I'd throw in my two cents. I have never been to Indianapolis, but my friend who lives near there isn't so fond of the city. I agree with all the arts/sports/neighborhoods mentioned about Pittsburgh, and it is an older aged city in some respects. However, there is a lot to do there for singles, in my opinion. There are a lot of other schools besides U Pitt in town (Carnegie Mellon, Duquesne, CCAC, Point Park, Art Institute, La Roche, PTI, etc...) so there is a HUGE college and grad student crowd, especially in Squirrel Hill. Two hot spots are the Strip District and "The Point," lots of clubs, bars, cafes, and cool markets. I can think of lots of other places, but you just have to go out and explore the areas. Neighborhoods are very distinct throughout the city, so there's a lot of choice. It's not NYC, Miami, or LA, but pretty good for a mid-sized city. Crime is average and better than a lot of other places.
I laughed when I read about the pierogies. My parent's moved to Ohio when I was 18, and I was shocked to find other people didn't eat them. But you can boil them and put some "I can't believe it's not butter" on top, and they're just as awesome without the fat. But the fries thing on salads is true. I still have to add them to have a "real" salad.
I'm just a Pittsburgher at heart, and as long as you root for the Steelers, you can be one too. 😉