I can tell you with certainty NOT to go too much past Coronado for beach action (Imperial Beach, I'm talking about you).
Any further south, and you risk Tijuana sewage/garbage. My aunt rented a condo on the beach in Imperial Beach, and just a short walk past the condos, there was an incredible diversity of trash on the beach -- dead seals, plastic tampon applicators, dead dogs....you get the point.
beautiful, with a relatively isolated town and expensive houses. The Hotel del Coronado is the best here, and you pay the $$$$ for it.
There are a fair amount of hotels along Mission Beach and (especially) Pacific Beach. I've always found it strange that most of the larger hotels are not on the beach in San Diego, as compared to Miami Beach. You have to drive a short distance to either Mission Bay or Hotel Circle.
Enjoy your stay....I like to visit San Diego, but it was just too boring to live there.