Atlanta-San Diego-Phoenix June/July 2012

hi everyone!
my mum and I are planning a roadtrip through the states next summer and I hope you could give us advice on where to stop and what not to miss and stuff like that. We already booked our flights from germany to ATL on June,29th and back from PHX to germany on July,20th. We love to be on the road and are not exactly the museum loving kind of people :D So we already have an outline of the route and some stops. We are planning to drive to Tallahassee first and see the Apalachicola Ntl. Forest, then head south to New Orleans via Panama City, then San Antonio(TX). We'd also like to see Albuquerque, Canyon de Chelly, Monument Valley, the Grand Canyon, maybe The Wave and Antelope Canyon then head west to Las Vegas and San Diego. Finally,we'd like to drive to Scottsdale. So do you think it is possible to do that in 21 days? Do you know anything about how getting a permit to get into 'The Wave'? And do you have any must sees on the way or any advice what to leave out or add? We went to Arizona last year and drove around for 10 days but we stayed at the same hotel all the time.
Thanks in advance, I'd really appreciate your help !