That's Sony Metreon. That's kinda cool for like 5 minutes.
They can go see a show, Phantom of the Opera is playing now.
They can go ride a cable car, go down to the wharf, eat some crab, see some sea lions.
They can visit the Golden Gate Bridge, go across it, and visit Sausalito; there's some nice little shops there.
They can take a ferry ride out to Alcatraz too.
Golden Gate Park is fun just to walk in. If they're into museums, they can go to the Palace of the Legion of Honor in Lincoln park. Outside the Legion is where many newlyweds go take wedding photos, it's very pretty.
It's a classical art museum. Then there's the MOMA downtown right near the Metreon, and that's obviously modern art.
They can go to the Palace of Fine Arts, which is another popular photo spot for weddings. And while they're there, they can go have some fun at the Exploritorium, a hands-on science museum which is lots of fun for folks of all ages (well to me it's fun).
They can drive down Lombard street, the worlds crookediest street. It's usually lined with flowers so it makes for some nice pictures too.
They can go up the Coit Tower, for some nice views.
Twin Peaks offers a nice view of the entire city. Very nice at night.
They can go to Ocean beach, the Cliff House, and have a nice dinner with an awesome view (food's just ok i think)
They can drive down Highway 1 (fun twisty drive) and go visit some nice shops in Pacifica, or play in the tidepools of Moss Beach.
They can even drive further down a bit and visit Monterey and Pebble Beach. They have some very nice Bed and Breakfast type places there.
Lots more that I can't think of now
-patchy