The best bit of advice you will get is to take warm clothing. Mark Twain is attributed as saying "The coldest winter I ever saw was the summer I spent in San Francisco."
San Francisco is an interesting place - Alcatraz, the pier area, good walks to the Golden Gate Bridge along the water front, good tram journeys in the city etc. but my geography and memory are not good enough to recommend locations to visit within 2 hours of San Francisco.