My best friend and I are just about to be finished with college (woot woot!!!)and, as a get-away vacation, we’d like to go somewhere. We have a 5k budget (He’s paying for half)

We’ve decided we’d like to go to California, and visit his parents in San Diego, and go to the famous San Diego Zoo.

We’d also like to visit some historical landmarks while we are there…
and here’s the problem:
There’s just toooooo many different places to go. Are there any significant landmarks that we can travel to? Have you been to any good places?
(like the best 4 or 5 you can think of.)

Details:
-sometime during Summer (10 day vacation)
-i need the assume worst weather