Depends what you're looking for, lp5151. Assuming you're looking for FHU pull-thrus long enough for your rig, you will probably want to avoid state parks (even though Starved Rock is quite nice.) Some we have used & thought were anywhere from pretty good to excellent:
Wyoming: Lyman KOA (more of a country "feel" and quieter than Rock Springs KOA
Cheyenne KOA - make reservations, as only a few sites will be long enough unless you unhook the toad
Nebraska: (haven't used Cabelas' CG in Sidney, but it looks ok if you don't mind road noise)
Best Holiday Trav'l Park, North Platte - you may need to unhook the toad here
Prairie Oasis RV Park, Henderson NE (near York) - former KOA, nice young owners, some sites are good & long, pretty quiet
Grand Island KOA - standard KOA, decent stop, pizza on site (will deliver to your rig)
Iowa: Des Moines KOA - some good long sites, not much road noise, decent place
Kellogg RV Park, Kellogg - behind a gas station, doesn't look like much but decent overnight, clean facilities, nice little burger joint in the gas station (popular with locals)
Illinois: Hickory Hollow CG, Utica - convenient to I-80, southwest of Chicago, not much road noise
