The tourist hot-spots are easy: old city for history (independance hall, liberty bell, constitution center, carpenters hall, betsy ross house, etc) art museum to run up the steps like a fool...err...Rocky, museums are nice (philly art museum, Franklin Institute, etc). If you have young kids with you try the please touch museum.
restaurants: I personally like Alma de Cuba (cuban food), Davios (italian steakhouse with LOTS more...get the cheese steak spring rolls...everyone does. seems odd in a high-end restaurant, but they are good, devon seafood, Tinto (tapas type restaurant...get the Octopus). Monks Cafe if you like belgian beer...decor is not great, but the food and beer make up for it.
lots more, but that should get you started.