There are two places I've found that make for great riding in Illinois. Most of the state (as you know) is flat, boring, and curveless. But for those of us living in this state, there is hope.
Starved Rock in the Lasalle, Peru, Utica, Ottawa area has fantastic roads, beautiful scenery and even some hills. It is most definitely worth a visit if you haven't been. Top it off with the fact that it is smack dab in the middle of some of the most boring slab-riding, and you have a nice reprieve from the daily grind.
Number 2 is Galena, IL. The town itself is something of a tourist attraction, but the architecture alone makes it worth a trip. There is an entire section of town devoted to historic buildings. US 20 just outside Galena makes for great riding. Curve after curve is decorated by amazing views of the hilly landscape. Wisconsin riders, this is a great place for you to visit, too. It's right on the border waaaay up in the northwest corner of IL.
If you haven't been to either of these places, I beg you, make the trip. You'll not be disappointed. Those of you who already have beautiful roads nearby, I hate you. I have to ride at least an hour to find some curves and scenery.
...except for ISU campus, there are curves and scenery there, too.
Living in a college town does have its perks.