Include Moab, the no. 1 offroad playground of America. See Arches (Thelma & Louise land). Rent small dirt bikes locally and head off into the Canyonlands NP. It doesn't get better than that.
We did also start in SF and did take the same route to Las Vegas, from there we did visit the Grand Canyon and from there we did go to LA and drove back using Highway one. If you like to see some small movies and read a short story. You can find it on www.LifeIsJoy.nl