Not much to do in San Diego...it's pretty boring here. Worst of all the weather is terrible most of the year.
Really though the touristy stuff is the way to go. All depends on what you're in to. The zoo is great, sea world is ok, beaches are decent, micro breweries all over, things like that. Depending on what days your here...you could go gamble on the ponies at Del Mar Racetrack which is about a block from the ocean in a very nice part of town.