How long do you have, over what timeframe?
It's probably worth taking a look at Laguna Seca and Infineon. NASA will be at Infineon this weekend.
Monterey is far enough away from SF, that I'd spend a full day there. If you're going to spend a full day in Monterey, check out the Acquarium. Go to fisherman's wharf for lunch or dinner.
For the best clam chowder in Monterey (and that's saying something) go to Fisherman's Grotto. It's on the wharf, on the left. They have a counter out front where you can get chowder in a bread bowl. Wander over to the far right-hand side of the wharf, on the other side of the shops. Very little foot traffic, and you can sit on a bench and enjoy chowder while watching the boats.
In San Francisco, they just opened up a new venue for the California Academy of Sciences. It's supposed to be fantastic. I would also hit Fisherman's Wharf for dinner. There's a really good restaurant, that I can't remember the name of, that specializes in Dungeones Crab. You must have Dungeoness Crab while you're in SF.