Actually, those three states are not in the Midwest. I lived in Iowa for a year and nearly died because the closest mountains were the Grand Tetons which were many hours away. I love the mountains. The Midwest is as flat as a billiard table.
I'd try the Smoky Mountains in Tennessee. I think I'm getting a hint of what you after and there are parks there that will fit the bill. If you want to hike there are trails that are not strenuous and there are plenty of diversions in the area as well.
