Marion is about the last stop going down I-57 where there's a cluster of motels. There's a Holiday Inn Express there and a couple of Comfort motels. The next place with a cluster in Pudacha in KY, never stayed there but from driving by they have the usual chains there. Sorry I can't help more.
I would make it to Paducah and stay there. If that is all the further we are going the first night we generally stay at I believe its either a Fairfield or a Courtyard for the Marriott points.
Check the Marriott site.
Its so much more psychologically better to get out of Illinois and be in Kentucky! Then you have at least one state under your belt.
We are leaving two weeks from today too!! Can hardly wait - I am leaving in the morning though since I am the only driver and making it to Macon Ga the first day!
I live in Carbondale, only a few miles from marion and there are several hotels there. There is a Drury Inn that is usually reasonably priced and most of them are pretty nice. There is an O'Charley's Restaurant (good food) a couple of blocks west of the hotel across the street from the Red Lobster. There is also a Sam's Club and a Walmart across the street, in case you forgot anything. Enjoy your brief stay in Southern Illinois!