The big spring break spot in California is Palm Springs (desert city about two hours east of Los Angeles). Parties all over town, though the locals tried to calm things down by outlawing thongs a few years back. I don't know the current status.
I've heard another spot is Rosarita Beach in Mexico (on the shoreline about 1 hour south of the border city of Tijuana)--take the toll road to get there within the 1 hour time frame I mentioned. Can't vouch that it has spring break stuff, though--but it is rockin' a bit in the summertime.
Can anybody in the LA area confirm that these are still the spring break spots they used to be?--Thanks,