Definitely San Diego. HOWEVER, be careful, the third week in July is the Comic Con International in San Diego. 144,000 geeks descend on the city and IF you can even find a room it is outrageously expensive. So just avoid the dates of July 22 - 27th and you should be fine.
Make sure you go to the Zoo!!! There is a new baby gorilla that should be on display summertime. You can see him now, but not within the troop setting yet. Oh man, he is the cutest!!! (His name is Frank....LOL LOL)