California is awesome in the summer tho! It's hot, but not as humid. Anyway, you have listed San Diego and Los Angeles already, so I thought I'd add San Fransisco to that
My best vacation ever was renting a car in LA and driving up the pacific coast highway to San Fransisco, stopping everywhere that looked like a cool place (Santa Barbara, Monterrey, and a couple of other places just to take pics of the coast and the ocean)... (of course you could start in San Diego and then go north. SD is seems to be a lovely place!)
Seriously, it was the best vacation EVER
Hope you have a great time, I LOVE LV