I'm surprised you've never been there. I guess you guys have some good places there by Detroit though to.
That's the thing, there's just a lot of options that all require some measure of driving so I usually just forsake the small stuff downstate and drive the extra 45 minutes to the northern hills since I gotta drive anyway.
If you're into park, check out Cannonsburg. They're really focusing on park and from what I read, it's one of the best terrain parks in the mid-west and I know for a fact it's only going to be better this season.