Sights to see driving across the US? -

I m planning a roadtrip from the Detroit area, to California. I wanted to go through the Northern states on the way there; I have a friend in Montana I want to stay one night with. On the way home, I want to drive through the south, stopping to visit friends in Arizona and in Arkansas.Since I m driving across the whole country, I want to see as many awesome sights as possible in between each friend I visit! Any cool ideas, I have no idea what s on the way; or what s worth going OUT of my way!It will be in the summer, and we will have several drivers. I plan on having to stay in hotels when I m not visiting friends. I just don t know where to go!

Picture Rocks MichiganMall of America, Minneapolis suburbs, MN Voyageurs NP MinnesotaCrazy Horse Statue SD Mount Rushmore SDBadlands NP SD Wind Cave NP SD Yellowstone NP, Wyoming Glacier NP MontanaZIon NP, UT Bryce Canyon NP, UTArches NP, UTVegas Strip, Las Vegas, NevadaGrand Canyon NP, AZ4 Corners (AZ UT CO NM)Monument Valley, AZPertrified Forest NP, AZSedona AZRoute 87A between Flagstaff and Sedona AZ Casa Grande AZ Carlsbad Cavern NP NMSpace Museum at Alamogordo NM Big Bend NP,TX Austin TX Alamo, San Antonio TX Hot Springs NP, AR Chicago IL