Muni Lines 29, 9, and 15
The famed 49 Mile Drive is a rightful chestnut for out-of-towners for its spectacular views of San Francisco, but visitors and locals without cars can get a decent abridged version for half the price of a gallon of gas with some clever maneuvering on Muni. Hop on an outbound 29 at the edge of the Presidio (on Letterman near Lombard), going west, which runs by Crissy Field and the Golden Gate Bridge before heading south to the Sunset, eventually passing Lake Merced, Balboa Park, and McLaren Park. At San Bruno Avenue, transfer to an inbound 9, heading north, to go through the Portola District, up Bayshore (no bothersome tourists around there!), and past the stately buildings of Civic Center. Make the last transfer to the 15 at Market and Third Street, for a ride up Kearny through the Financial District and Chinatown, ending near Fisherman's Wharf. It won't leave you exactly where you started, but you'll have seen a hell of a lot of the city. Best of all, the trip fits snugly into the hour and a half allotted with a transfer.