We signed our son up for gymnastics through the Arl. Hts. Park District when he was 3.5. He has loved the program, and has participated in three consecutive sessions now. It is actually run jointly with the Rolling Meadows Park District, and the facility is in Rolling Meadows. They do a great job of exposing the kids to of the various equipment. The class size is about 15, but there are 3-4 teachers in the class at all times and after warm-ups they always break into 3 smaller groups of 4-5 kids each. I do know that the classes fill up very quickly (as in the same day that registration opens). I've always just been aware of the first registration date and made sure to log in that day and have never had a problem getting a spot. I don't know anything about any private facilities.