YOSEMITE!!! way better than the Grand Canyon. Though the GC is nothing to turn up your nose at.
Napa Valley is just an hour or so northeast of SF and certainly worth a visit.
Go to Vegas (the place is gaudy beyond belief and there is the off chance you could leave town a millionair) drive through Death Valley to 395 north to Lee Vining. Make a left there to Yosemite. Drive up route 49 through “Gold Country.” Just a lot of fairly cool little towns that sprang up during the '49 gold rush. Turn left on I-80 at Sacramento and tool on down to Napa and Sonoma Valleys. Spend 3 days in SF (great town. Do Alcatraz, the Golden Gate Bridge, Haight-Ashbury, Chinatown). Drive down the coast highway. With a little planning you can stop and see several of the missions built in the late 1700’s early 1800’s. Spend some time in Monterrey and do the 17 mile drive. It’s sort of depressing though, looking at all those homes sitting on lots that after saving for 20 years you couldn’t afford a down payment on. Stop at the Hearst castle too.
If you’ve never driven on the “wrong” side of the road before take your time and pay attention. It’s harder than it sounds. During our trip to Oz every time I didn’t think about it (and some that I did) we were on the wrong side of the road.
In the event you get pulled over by the state patrol rely very heavily on your accent. We find it cuter than hell. Sprinkle your speach with all sorts of Australian slangy kind of things and you’ll probably get off with a warning.
Enjoy.