Thing to do in San Diego?

Wow, where do I start....
Mission San Diego, the first and oldest mission in California and still an active Catholic Church is a must see.
Go to a Padres game at Petco Park; a really beautiful facility.
Sea World is nice for a family outing.
If you are willing to drive a bit, Disneyland is about an hour away in Anaheim and pretty much anything under the sun is in L.A., about 2 hours away.
That's just off the top of my head.
If you want to know about anything specific just ask.