Last summer a friend of mine and I took a month-long roadtrip around the US. We started from New Jersey, and went:
Philly->Pittsburgh->Chicago->Milwaukee->Western Iowa/Omaha->Black Hills in SD->Butte, MT->Seattle->Portland, OR->San Fran->Los Angeles->Grand Canyon-> Albquerque, NM->OK City->Birmingham, AL->Raleigh, NC->Back home.
It was a ton of fun, probably the most fun month of my life. We couchsurfed on the way, as well as staying with some friends. And couch surfing was seriously awesome, we met some great, interesting people (
seriously check it out if you're going anywhere far, cuts cost and is an awesome way to meet people).
Edit: Also wrote a
blog for part of the trip, lost interest before we finished the trip =/
To answer your question, in your area: the Grand Canyon is awesome if you're outdoorsy, or if you've never been there (we were going to camp there for a day, but went to a hostel instead). You could also make it to LA, and see the beaches over in Santa Monica. It's fantastic there, the best beaches I've ever been to and the weather was sweet. Also tons of site seeing there. And the drive between SF and LA is the best drive in the nation (if you take US 1, the scenic route), but for your time frame probably too much driving.