J.H.
If you don't want to have it at a park and want something with a little more structure I would try the zoo. If you are in the sacramento area you could also try fairytale town. They have a King Arthur package that is like 9 dollars a person and I think it includes party favors, a bannor with his name on it and the cake. Some packages even include the meal for the kids. Then they also get to run all over the place.