Road trip suggestions?

If you were planning a cross-country road trip, what are some places you would make sure to include?
Here’s some starters to get the ball rolling:
I’d like to see Crater Lake again.
Lassen Volcano Park.
I’ve never seen the Grand Canyon.
Nor the Dakota Badlands.
Niagra Falls.
Yellowstone and Old Faithful.

C’mon, I’m sure you folks have got some brilliant ideas!