Thing to do in San Diego?

Just flew home from San Diego, logged into SR and happened to see this thread.. I stayed at the Marriott Marquis, right on the water and it was beautiful-- but unfortunately was there for work so didn't get to enjoy it much .. It's a special kind of torture when you're trapped in seminars and classes all day, but they have you overlooking boats, water and sunshine.. Did get to eat at a decent restaurant in the Gaslamp though.. Would like to go back when I have more leisure time.. Oh, and did get my first In n Out burger in years when we spent the prior weekend in Los Angeles.. So good.