Hi Shar & Gord,
I suppose it depends how fast you need to travel -if fast go I-80 stopping at Iowa City-Herbert Hover National Historical Site; then divert to 6 and go to the Amana Colonies near Homestead; Trainland USA near Colfax; Stategic Air & Space Museum between Omaha & Lincoln; Pony Express Station at Gothenburg; Buffalo Bill Ranch near North Platte and at Rawlins, WY take 287 to the Grand Tetons & Yellowstone.
If you have the time I would cross at Sarnia and take I-69 to Angola,IN then head west on 20 stopping at Shipshewana (Tue & Wed huge Fle Market); Elkhart for the RV Hall of Fame (note it has moved); follow I-80 to Des Moines, IA; north to 20 and follow it to WY. Lots to see enroute and the best guide is 'Road Trip USA' (Jamie Jensen a Moon Travel Handbook) which gives losts of places to stop and what to see including the Cardif Giant in Fort Dodge, Ashfall Fossil Beds then go north on 385 to the Wind Cave National Park and then Mt Rushmore, Crazy Horse and maybe backtrack a bit to the Badlands National Park; then back down to 20 and head to the Grand Tetons & Yellowstone. Did not do the Beartooth but strongly recommend you visit the Glacier National Park and then in Alberta the Waterton National Park ensuring you take the vintage car tour of the 'Going to the Sun'. Hope that gives you some ideas. Have a great trip and, if you have time, consider using both WBCCI Courtesy Parking and maybe one or more Club rallies enroute there or back.