It appears that just about anything can be turned into a playground. Don't believe me? I can prove it with an Illinois park that is full of playground equipment, but it used to be a missile launch site during the Cold War era.
Jurassic Gardens in Volo, Illinois offers a true prehistoric experience with animatronic dinosaurs, real dinosaur fossils and skeletons, and SOO much more.
If the awesomeness that is Hurricane Harbor Rockford is a little too much for your young kids, check out Otter Cove Aquatic Park in St. Charles, Illinois.