How old is the child in your group?
On our last visit we went to:
Alcatraz
Ft. Point - mid day they have a cannon demonstration that is fun
Took 2 walking tours thru City Tours (free), 1 of China Town and the other was the Golden Gate Bridge.
Over the bridge to the N. is a fascinating place, Pt. Bonita along with Rodeo Beach and from there we drove N. to Muir Beach
The Cable Cars are really fun - The line that runs from Union Sq. to the Wharf can be very crowded but the one that runs from Market to VanNess is less toursity and was lots of fun. It goes up an over Nob Hill near the Fairmont, the Mark Hopkins and Grace Cathedral. We hopped on and off on Stockton Street on the outer edge of ChinaTown.
California Academy of Sciences is a beautiful museum but my DD prefers the hands on Exploratorium
The aquarium by the Bay is ok, we buy CityPasses and admission is included otherwise I would not pay the entry fee, its not worth it IMO. You want an aquarium, stop in Monterey and go to the Monterey Bay Aquarium.
If I only had 1 day here is what I would do:
I would start off with a walk to at least the mid span of the Golden Gate Bridge. From there, proceed to ChinaTown, get off the main street and explore the markets, simply amazing. The food is good too, we love the Washington Street Bakery and Restaurant on Washington St. below Stockton St. The VanNess/Market cable car line runs just south of China Town, walk down there and take the cable car over Nob hill and back. From there I would walk Columbus Ave thru Little Italy down to the wharf. Check out the sea lions and the street performers, have some crab or chowder in a sourdough bread bowl, I would finish up the day with an Ice Cream Sundae at Ghiradelli Sq.
If it were me, I would drive to the Bridge in the morning before the wind kicks up, then return the car to the hotel and take Muni to China Town (1 bus) walk to the Wharf, walk to Ghiradelli then take Muni back to the motel (1 bus) If really crunched for time, take a cab. The ride from ChinaTown to Ghiradelli Sq. cost us under $10 including tip and he drove us by Lombard (the crooked street)
We go to SFO a couple of times a year. I know there are several Dis'ers who live in that area. I grew up south of the city and take my kids often for all the museums, history etc.