I lived in SD for a few years. It basically sucks to live there unless you have a lot of money, at least in my opinion although its hella better than living where I do now(in NC which REALLY sucks). The zoo is awesome, I had yearly passes and used to go at least once a week. One of the best in the country! For nightlife, you may want to either head downtown and hit up some clubs like On Broadway or Montage(on straight night that is!).
Maybe cruise up to La Jolla and check out the beach and the seals. Its a nice area to visit and has some decent restaurants. I recommend the Italian place called Trattoria Acqua, very good food.
The weird thing is SD has mostly ugly chicks, I mean I lived in Florida for a long time so I have that to compare to but Cali chicks are dogs compared to FL chicks. Not sure why but its true. Too many people think its cool to dress like a skater well into their 30's in SoCal. Oh well. Whatever.