California???

Okay.. I have a question for all of you who are familiar with California. A friend and I are going to be going on a trip this summer! We are only 18 and do not plan on driving. Basically we want to know what city in California would be best for us. We like the beach, warm sunny weather, there needs to be lots of stuff to do and needs to have a great night life. I've never been to any of these places but these are what we had in mind:
San Diego
Santa Monica
San Francisco
PLEASE HELP ME GUYS!!! Also, I needs to be safe! We will be walking and taking public transportation! Thanks!!!

I've always loved San Diego, for all of the things you are seeking. Try Mission Beach, or Pacific Beach -- the party never stops. Bob