You can always do the highway 1 trip from SF down to Big Sur. Like stated above, on a holiday it could be a nightmare but there's quite a bit to see on the coast. You can hit SF, Pacifica, Santa Cruz, Monterey/Carmel, Big Sur. There's some decent skateparks in most of those places, too.
Yosemite is pretty awesome, and north of SF you can hit up Russian River/Guerneville which is a favorite of mine.