I just got back from San Diego and my experience was that the traffic really wasn't bad. We stayed on Harbor Island since my wife was there for business and her company was paying. Didn't take long to get anywhere.

You didn't ask for recommendations on activities but here are mine anyway.

See the Zoo and if you can get up to their Wild Animal Park it's well worth the drive. There's a $59 ticket that gets you into both parks and is valid for 5 days. It includes extras like the Zoo's guided tour bus, express bus, Skyfari sky ride, and the wild animal park's Journey Into Africa.

I also strongly recommend Cabrillo National Monument . You'll find a spectacular view of San Diego along with the beautifully restored Old Point Loma Lighthouse. The harbor tour is also very nice.

Enjoy your trip.