Closest is going to be KS Rocks. Followed by Tuttle, SMORR, Flat nasty, Disney Ok, and a few others scattered through Mo that I'm missing. I am a park official for KS Rocks so I'm a little biased since I wheel there the most. Ks Rocks is a great place with some very technical stuff for the big boys all the way down to stuff a stock KJ can run without issue.
We do have a few events at the park coming up:
Sept 5th is the bi annual wheeling 101 class and night run
Sept 13th is the Fall Crawl. It's an novice rock crawling compitition.
Oct (forgot the date off the top of my head) is out Creepy Crawl. Family oriented with games for the kids, costume contest, and a haunted trail ride.
If you have any questions or more info on all these events check out Kansas Rocks Recreation Park