R.W.
You've gotten a lot of great replies so far, but I also have a couple ideas. The Petland in Bolingbrook does parties (very reasonably priced) where they bring different animals out to show the kids and they can get up close with them. Splash Station in Joliet is pretty reasonably priced to do a party and also the park districts in Plainfield and Joliet do pool parties as well. Hope that helps, we did my daughter's 3rd birthday at the bowling party in Channahon and it was by far the easiest and cheapest (but still nice) party I've ever done! Good luck!!