Thanks for the advice. I think I would prefer to stay in the parks so will book them up. I have just been looking at your report from your trip and the places sound amazing!! My rough plan at the moment is:

San Francisco 2 nights
Napa Valley 1 night
Yosemite 2 nights
Through Death Valley to Las Vegas (should we stop somewhere on the way?)
Las Vegas 2 nights
Bryce Canyon
Lake Powell
Grand Canyon

I took these places off routes I found online. Not sure yet what route to take back from the Grand Canyon to Los Angeles. If you have any suggestions on this or any recommended places to stay I would apprieciate your advice. Thanks.