I'll second what Dave says - definitely take a spin up/down 101, it's a great drive. Check out the Hearst Castle along the way (http://en.wikipedia.org/wiki/Hearst_Castle). Though if you've seen something like Versailles you'll laugh to yourself when you hear the tour guides talk it up like it's the most amazing thing since sliced bread... but it's worth a visit.

IMHO give LA a miss (it's a hole) and spend some time a bit further north along the West Coast - if you can push it, head all the way up to Seattle or even Vancouver.

And if you can squeeze it in, stop over in Chicago when you're traveling from the West Coast to the East Coast... yeah I'm biased about this (being my hometown and all) but it's a great city to visit!

East Coast wise... one alternative would be to stay north, visiting places like Boston / D.C. / Philly as well as NYC.

Wherever you go you'll have a great time, just be prepared to stack on about 10 kilos!