Of course there is.

But really, you've got sort of a tough decision. You could easily spend some very quality time in the Art Museum, walk around the Univ of PA campus, do the typical cheese steak tour, maybe take in the US Mint, walk Penn's Landing. However, I think you get more bang-for-your-buck with the extra time in DC.

Oh, if you're doing the Liberty Bell and Independence Hall, you definitely want to do the National Constitution Center. (If you go to Betsy Ross' house, stop along the way to see Ben Franklin's grave. Turn around and you'll be staring at MTV's Real World Philadelphia house...ok...another thing that may only interest me.)