I think www.mtbr.com has a trail review section. You should be able to find a decent list there. I ride at Comlara in Bloomington-Normal, which is decent but not worth a drive from Chicago unless you're desperate. I have heard a lot of good things about a couple trails in the Peoria area, but have not had the chance to get over there. There is a place near Peoria that has a good amount of DJ stuff, and a bunch of singletrack too, I think. Hope this helps, and definitely check the mtbr site, if only for a list of trails.