My wife and I did Philly last year and it was awesome~! Reading Terminal Market is a must an be sure to try a Philly Pretzel with mustard. Quite different and quite good! Constitution Hall is a must (arrive early as the lines can be long), the Liberty Bell, the double decker bus tour (lets you get off and on at various attractions) and great restaurants galore. Jim's for cheesesteaks for sure and of course, the Italian Market (especially DiBruno's). We found people to be very friendly and helpful and watch for the uniformed guides in the downtown area that are at almost every major street corner. They serve as goodwill ambassadors for the city and do a great job; very knowledgable. It you venture around the area, go to Longwood Gardens and Valley Forge. Philly is no more dangerous than any big city so just use common sense. We walked all over both day and night and never encountered any issues.