If you were going to be in Southern California what would you do...?

I'm going to be in North San Diego area for my Spring Break and also this summer. I'm 19 so where are the 18+ clubs? Any suggestions? Also for a few weekend trips where would be most fun? Sacramento, San Diego, LA, Anaheim, etc... I'm open to different all environments- party or relaxation! Also is Tijuana unsafe at the moment? I just need a general list of things to hit during my stay- keep in mind I am young and not rich haha. Thanks!