W.M.
I agree about trying the park districts to see if you can rent a space. Elk Grove has a great park district facility with an indoor playground and carousel, but I don't know if you really have enough kids to justify it. My friend had a party there, and she rented the space (don't know the cost) and ordered the pizza and cake herself. She also probably had almost 100 people- the place is huge. Check your own park district first because the cost is probably lower for residents. Good luck!