For those going to Philly--the underrated Academy of Natural Sciences (very very close to the Franklin Institute) is also wonderful with about 4 floors of excellent animals, dinosaurs, etc. Also, outside of Philly there are some terrific places:
Mercer Museum & Fonthill Mansion (the ultimate collector's museum),
Hadley Museum (Delaware--excellent hands on science from DuPont sponsorship, I think)
Independence Hall & Liberty Bell are so crowded during normal vacation times so I really encourage homeschoolers to go off-season. There is a ship at Penns Landing that is a museum, too.
Herrs Potato Chip factory tour (more than an hour away, but a memorable tour for the kids)
Also, Crayola factory is a couple hours away I think.
For those in the NM area, we have Carlsbad Caverns, White Sands, Alamogordo Space Museum, lots of art museums, Historic sites like where Billy-the-kids holed up, beautiful vistas, indian pueblos & ancient ruins (Gila Cliff Dwellings, Bandelier, Abo, Salinas, etc.) EXPLORA science museum, National Atomic Museum, Rio Grade Zoo, Albuquerque Biopark & Aquarium, Rio Grande nature Center, lots of wildlife preserves, hot springs, etc.
