Conneticut to Washington

My husband and I are moving from CT to WA and are driving with our little dog, a dachshund. We are taking I-80 west through PA, OH, IN, IL, IA - then I-29 north to I-90 all the way to WA. Our interests are very wide and are allowing time to stop at any cute scenic outlooks or unusual sites. So far I can only find Mt Rushmore & Devils Tower...any other selections in october?? All thoughts would be appreciated - picnic sites, monuments, historical areas, weird attractions and cool places to eat...anywhere.
TIA for the suggestions!!

Don't forget the Corn Palace, Badlands and Wall Drug. If the snows haven't hit yet, you are perfectly situated to hit Yellowstone, and the Beartooth Highway to get in there is spectacular.

Going to Yellowstone, with a stop in Cody on the way, would be a good detour if you have time for it.

If you opt to stay on I-90, stop at the Little Bighorn Battlefield Monument (by the merge of I-90 and Hwy 212), Pictograph Caves is just south of Billings, and Greycliff Prarie Dog Town (just east of Big Timber). Big Timber is a nice place to stop with a waterslide park and hot springs. Lewis & Clark Caverns, about mid-way between Bozeman and Butte is nice. Also the Grant-Kohrs Ranch National Historic Site near Deer Lodge a few miles past Butte.

Really, you're driving through majestic country whichever route you decide to take and you won't have to search too much to find terrific places to stop along the way.