RP1955, your trip sounds a lot like the first leg of our planned trip. We're leaving VA in March and seeing a bunch of things on our way to Grand Canyon, then eventually the redwoods (all we're interested in in CA) and Crater Lake, OR. We'll visit my sisters in Washington State and then back across via I90 IIRC, see what there is and on towards home. Planning about three months.
Found something called the ultimate cross country trip across US seeing all the major sights and have been playing with that map...if I can only find it...