Hello M.,
I'm not sure what you are willing to spend but there is this place in New Hope Pa,, it's not too far away, and it is called Giggle Berry Fair you can look it up on line as well they do have a web site, this place is awsome, the have a little arcade center, then they have this thing that they call a moutain, when you walk in the moutain area there are tons of balls that are soft, plus they have guns that you can use to shoot the balls out of, then you get to climb the moutain with your son, and they have different activies to do at different levels, it is great, then they have a discovery zone where they can play house put on a puppet show or play dress up, my daughter really loved it and it really wasn't that much money to spend the day there, plus if you don't want to buy your food thier there is a Mcdonald's not that far and they stamp you hand so you can go back to the place again
hope this helps
good luck
S.