Really is a great city. Hit the Reading Market for lunch, it's a must. The Parkway is nice, great photo ops and museums (Rocky steps). Rittenhouse Square area has nice restaurants and upscale shopping. South Street has a quirky nightlife. Comcast building has a unique video display/show in it's lobby. Eastern State Penitentiary gives tours (see Al Capone's humble abode). There's a great zoo a few minutes from downtown (Zoo Balloon is another great photo op). Great jogging/biking along the Schuylkill River. Independence Hall, the Constitution Center, Betsy Ross house, the US Mint, and Elfreth's Alley are highlights of Olde City. You'll have no problem filling your time.