L.M.
There have been some great suggestions here. I run a website that you could check out http://www.playgroundbuzz.com. It is a directory of fun kid venues in the Philadelphia area, and just about everyone offers birthday packages - from zoos and art centers to libraries and museums. Also take a look at the "Classes for Kids" tab - if you child has interest in art, sports, music or anything else, most of the sites will provide party information as well. You could search on your zip code under "Activities Search" tab to find some venues in your neighborhood. Good luck!