Agree with Henry Ford Museum & Greenfield Village, and while you're on the U.P. (upper peninsula) visit the Whitefish Bay shipwreck museum. Both fascinating. Allow a full day for the Henry Ford. Also agree on Glacier. I highly recommend the full day "red bus" tour.
If you haven't been to Yellowstone, definitely go (on your way back probably best)- I'd advise advance reservations, which may be found a little easier outside the park. (West side the best.) The Columbia River gorge along I-84 in Oregon for sure, and through Idaho, follow US 20 instead of I-84 east of Boise for a little bit different scenery; stop at Craters of the Moon National Monument - a nifty and very unique "little" park. They have a dry CG there in the park and there's a decent KOA about 20 miles east of there in Arco that makes a good homebase for Craters. (Unique little town on its own too.)
Along I-15 in Utah take a detour to visit Bryce and Zion NPs.
Sounds like a fantastic trip! Enjoy & safe travels!