What scenic routes are there from Nashville to Minnesota and from Minnesota to Seattle?

I want to drive from Nashville to Minnesota and then head west to Seattle. I know that I want to see the Badlands, South Dakota/Black Hills/Mt. Rushmore/Little Bighorn, but I was wondering if there's anything else I should have on my destination list. I have one month.What scenic routes are there from Nashville to Minnesota and from Minnesota to Seattle?
i live in Minnesota! Haha if I were you, I would drive up to Duluth, it's a town up north in MN on Lake Superior. Super pretty, and I LOVE the lake. I've been to the North Dakota badlands, those are pretty. There is also a small town called Medora in ND, where they put on a cool play on this outdoor stage. It's nice