Again, Reading Terminal Market. In particular, D'Nics Sandwiches and the Pennsylvania Dutch place --look for the bonnet-wearing women. The make an apple-dumpling desert thing that clocks in at about a kilogram...
Have one drink at the Ritz Carlton. Its opposite City Hall. The building is a replica of the Parthenon, and you can sit on a comfy couch directly beneath the huge marble dome...
Get a pork Italiano sandwich at Tony Lukes on 18th {?} and eat it in Rittenhouse Square park, if the weather's nice...
Play a round of darts and drink a Belgian beer at Nodding Head, or get seafood at the Sansom St. Oyster House {both on Sansom between 15-16th}. You want local? Go to Dirty Franks on 13th and Pine for happy hour....
Or get Indian food at Minar Palace, also on Sansom {great little hole-in-the-wall}...
Walk up to the Art Museum, if you have time. Start from Love Park {opposite City Hall, NW corner}.
Avoid the Liberty Bell, unless you like annoying barricades.
If you have any time in the evening, get bar food at Fergie's {Sansom, between 11th and 12th??} and stay for Quizo...