We walked all over Santa Barbara. I love their downtown mall and I am not a shopper, but it is neat that you barely even know it is there the way it is built into the block(s). There is a lot of very good food on that main street!
If you go to La Jolla, go down to that beach area to see the seals. We have walked quite a ways up and down a path nearby. Take the sidewalk north to get to the path.
The first time we visited San Diego we stayed in Old Town. That was fun, but I didn't care for the "fried lobster" that one place serves. The rest of their food was fine. I just expect lobster to taste like Maine lobster, I guess.
We stayed in the downtown area this last time and ate in some of the Gaslight district places. We really enjoyed that. Old Town seems a bit safer at night, though.
Those surfers are fun to watch up and down the coast. I am not sure where we were, but there was some major surfing going on north of La Jolla last fall (2007)