Assuming the weather will be good at SFO
(in which you will land coming in from the south), which side you should sit on depends on what you would like to see. If you sit on the left, you will have awesome views of the SF
suburbs and the SF
Bay shoreline, airport hotels(esp.Sheraton, Hyatt, Marriott)and, once on the ground, good views of the terminals and a wide selection of aircraft. If you sit on the right, you will get all water views with a cool overhead view of the San Mateo Bridge. The East Bay and Oakland will be off in the distance and sometimes you can see downtown SF
way, way off in the distance.
If the weather is poor or windy, the planes land from the north. I have only landed this way once, but sitting on the right side of the plane afforded me amazing views of downtown SF
, the Bay Bridge, 3Com(Candlestick Park) and the Bay. I am not as familiar with arrivals from this direction, though, so I am not the best authority on it.
Hope this helps.