Boston to Seattle in May

In a few weeks I'm moving west from Boston to Seattle in a mini-van. I don't have a lot of time to waste, but want to make the most of the trip. Yellowstone and Mt. Rushmore seem like good stopping spots, and I'm thinking seeing some of Amish country for OH/IN, but I'm up in the air for others, especially in the central and eastern parts of the trip. I would like to avoid major metropolitan areas and stay in natural beautiful or interesting areas.

Any suggestions for PA, OH, IN, IL, IO, MN, WI, MI, SD, ND or MT/WY/ID?

Would love ideas, especially close to highways like I-80 or I-90.

Also this is my first cross-country trip and I'm doing it solo. How many hours of driving, realistically, can I expect to cover each day, or in a row?

Thank you!

Duncan

Montana: Glacier National Park, Prairie Dog Town (or whatever its called) near Wycliffe, Copper King Mansion in Butte, Our Lady of the Rockies in Butte

Wyoming: Devil's Tower, Cody (lots of museums and other fun stuff), Yellowstone, Grand Tetons

Idaho: Craters of the Moon, Hell's Canyon

Have a great trip!

If you are into amusement parks; in Sandusky, OH (about 10 mi N. of I-80) has Cedar Point. Great place if you love roller coasters.

For Amish country recommend Shipshewana IN or Middlebury IN recommend eating at least at the Das Dutchman Essenhaus in Middlebury. Quick on and off the IN toll road.