All kidding aside, Philly has some cool stuff. Next time we'll have to stay longer. We went to the Please Touch Museum (an awkward name for a kids' museum in this day and age, but it refers to a commendable mission of engaging all the senses of a child through some excellent displays and exhibitions -- a museum that actually encourages its patrons to interact with its collections).
The museum building is grand and the sights are spectacular. My favorite was the Alice in Wonderland themed section, but there plenty of other attractions to keep the attention of the little ones, while grown-ups could have a fun time too -- River Adventures, Flight Fantasy, Rainforest Rhythm, and more. My daughter loved the full-sized fully-refurbished Dentzel Carousel, which original resided in Woodside Park.
If you have kids and happen to be in the Philadelphia area, check it out. You'll have a great time.