dhampyresa

Golden Gate Park. Notable landmarks that a local would probably recognize:

de Young Museum
Bison paddock
Model boat sailing lagoon
Dutch windmills near the ocean

A main thoroughfare within the park closes to motorized vehicles on weekends. Bicycles (and some people for whom two wheels is too many on unicycles), skateboards, scooters, roller skaters, just plain walkers.

Other locations:

Palace of Fine Arts
Legion of Honor Museum (complete with a casting of Rodin's Thinker in the courtyard).
Crissy Field
Fort Point (can be shot with or without the Golden Gate Bridge in the background)
Ferry Building
Civic Auditorium (there's a reason it now also honors legendary promoter Bill Graham)
Fort Mason (the historic buildings, and also Fort Mason Center)
Aquatic Park. Popular starting/finishing point for people who swim in the Bay, and don't mind the currents and the low 50F/low 10C temperatures.
Pier 39 (this is where the piers with the sea lions actually are; too many productions would make you think they're at Fisherman's Wharf) -- it's an outdoor tourist shopping mall, so locals don't usually come there unless dragged by visitors.
Rent-by-the-hour mini electric cars
Ghirardelli Square
Hallidie Plaza (Powell Street BART station, south end of Powell/Mason and Powell/Hyde cable car lines, and informal pissoir for those overnighting in the streets in the vicinity)
UN Plaza. When the olive trees get cut back there each year, they look absolutely otherworldly. And if you set up your shot right, you can get them as the only bit of nature in a concrete landscape.

Bits of wtf:
Vaillancourt Fountain
Twin Peaks with Sutro Tower
Filbert Steps (yes, it's an actual city street with actual addresses. It also goes up a hillside for 700ft/200+m at roughly a 30% grade.)

Other oddities:
Baseball stadium. Right on the water. With the SF Opera presenting a production on the field.
Or during an actual baseball game. With dozens of kayakers out on the water (McCovey Cove) hoping for someone to hit a ball far enough to reach the water. (Happens a few times a season.)
The Blue Angels (US Navy precision fighter team) flying over the city during Fleet Week. And the roar waking people up, setting off car alarms, and interrupting conversations citywide as they practice before their show.
Available, legally permissible parking space. Always a hoot for locals to see someone driving around the city and pulling into an available spot just outside their intended destination.

One last bonus:
Microbrewery. Filled with twenty-somethings dressed in some iteration of "business casual". Served by bartenders dressed in some iteration of ripped jeans/T-shirts featuring bands popular 10-20 years previously, and outrageously styled and colored hair.

I can probably dig up a few more if you'd like.