Actually April is NOT the time to travel in the U.S., it is tornado season. Better to wait until May if you can - less storms.
As for your trip. Personally I would go to South Dakota and area. I have been through there, as well as Colorado, New Mexico etc. and the SD is vastly underrated. Montana is also stunning. Why not a trip to the pacific north west - hit Oregon, Washington State and maybe come back through the Canadian Rockies?
Bookmarks