Can't help you with motels, but take OH 2/U.S.6 from Toledo - western suburbs of Cleveland, instead of I-80/90. You'll be right on the lake, and there are plenty of quaint towns like Sandusky, Vermilion & Marblehead (not too far off OH2). If quaint is your goal, then head south after hitting Cleveland, and hit Holmes County. It's the epicenter of Amish life in OH (which, BTW, has more Amish than PA), and it's the definition of "quaint."

I grew up in OH, and I think you may have too romanticized a notion about "quaint motels." The ones I saw were either seedy, have become places for illegals to live, or rent rooms by the hour. Try B&Bs instead.

Quaint towns in Michigan would include Frankenmuth,Saugatuck,Silver Lake,Ann Arbor,Charlevoix and Tawas City.
Have fun!

For Pennsylvania, the town of Zelienople (Cranberry Twp.) is described as quaint. There are several B&B's including the Inn on Grandview. I don't know why you want to visit the Rust Bowl.
You may wonder what a guy from Oregon knows about PA-I was born there and worked for the state for over 30 years.

There is a recent Amish thread on here you may find helpful, I'll see if I can track it down.