If you go through Iowa on your trip west, get off I-80 at Iowa city and get on Hwy 6. That will take you through the Amana colonies. It's a really neat place to go. Then follow Hwy 6 until it meets I-80 again.
Get off I-80 at Grimes, go into Grimes and follow highway 44 across western IA. It will take you back to highway 30 about 10-20 miles from the Neb/Iowa border. It's a beautiful scenic road with lots of nice old farmsteads along it.
There are a number of antique malls in a town called Casey, which is about 10-15 miles south of Hwy 44.
There's also Elk Horn a couple miles south of 44, which has a windmill and tourist center.
I know you mentioned you like to stay away from big cities, but I also recommend viewing the Salisbury House in Des Moines.
If you happen to get to Des Moines during a meal time, go a couple miles past the Grimes exit to Hickman and go to the Machine Shed Restaurant. It's delicious. And while you're there, you can see Living History Farms, where you can see an old fashioned farm running.
Me, my DH, my DD (7) and DS (3)
'09 Puma PF295BHSS 33 1/2' Bunk house (Finally-a camper I'm proud of!)
'04 Ford F-350 crew cab 6.0L PowerStroke diesel "the haulin hawg"
Owners of an auto repair shop-Working hard to play hard later
Try driving up and/or down 395 in CA and Nevada: Sierra Nevadas rise to one side, desert drops away to the other. Lots of beautiful sights and interesting places to stop/see (Whitney Portals, Mono Lake, Mammoth Lakes, June Lake Loop, Death Valley, Reno, the 'back entrance' to Yosemite, etc etc.).