San Francisco is just awesome. The Legion of Honor Museum are not to be missed. Yerba Buena Gardens (South of Market neighborhood) is also awesome and next door is the Metreon theater, which is shiny and offers IMAX movies.
The California Academy of Sciences is a great place to explore with a rainforest, huge aquarium, planetarium shows and is inside Golden Gate Park. You can also walk over to the de Young Museum and can go inside and take the elevator to the roof (all for free) where you are greeted with a beautiful 360 degree view of San Francisco and the bay. You can also find the Japanese Tea Garden inside the park.
Ferry Building marketplace on the Embarcadero has many local, well known restaurants and shops. It is a great place to walk through if you have a chance and is only about 1 km from the Marriott Union Square.
Note: Golden Gate Park is not next to the Golden Gate Bridge. If you want to walk from one to the other it is a good 3 mile walk from the CA Academy of Sciences north through a neighborhood and then through the Presidio. If you have the time, you can walk along Ocean Beach and take the Lands End Trail along the coast then continue walking to the Bridge through neighborhoods and ultimately the Batteries to Bluff Trail to the south side of the Golden Gate Bridge (this is a 7 mile walk).
Cool things to check out in SF:
Culture and Museums
Shopping
Outdoor Activities
Miscellaneous
Shopping
Tourist Attractions
Culture and Museums
Shopping
Outdoor Activities
Tourist Attractions
Culture and Museums
Shopping
Physical Activities
Culture and Museums
Breweries and Wineries
Outdoor Activities
This region is best known for its vast expanses of parks and natural beauty. While public transit does connect the North Bay with the rest of the Bay Area (buses and ferries), much of it is only accessible if you have a car to drive.
Outdoor Activities
Stanford is in Palo Alto which is about a 18 minute to 30 minutes drive (a $130 cab ride each way) from San Francisco or you can take the CalTrain for $16.50 round-trip per person.
The University of California at Berkeley (Cal) is very easy to get to via the BART subway system right out the front door of the hotel and it drops you off within a few blocks of the Cal campus. Round-trip would be less than $8.90 a person (even cheaper for youth). The Cal campus is very beautiful and quite an experience.