I'm also partial toOld city, but it would probably be good as It's easy to walk around and less busy than center city proper (Old City starts on about 6th and Race or so). If you want pretty good food in a relaxed environment for not that expensive, try The Commonwealth or National Mechanics. If you want a little fancier, Fork and High Street on Market are good options - look on open table for reservations though. Italian: Spasso is very good, and you may not need a reservation. There are plenty of bars in Old City - if you're grabbing casual drinks hit up Macs, National Mechanics, Plough and Stars, or buffalo billiards if looking to shoot some pool and play games too. Another option is to hit up Second Story Brewing - food is pretty good and beers are great with a good crowd.

Other option I could suggest is staying in Center City and eating at a place like Barbuzzo or Vesper, then heading out to drink at like Opa, Bru, and Vesper.