Here some things to do:
Coffee: Get Blue Bottle, many locations in SF. But, the Mission location inside the Heath Ceramics is pretty awesome.
Ocean Beach/Sutro Baths: It will probably be foggy, but amazing to spend a few hours.
Marin Headlands/Muir Woods (if you have a car): Will be busy, but a real taste of Cali.
SFMOMA: The new sfmoma building should be open by mid-may so worth checking out.
Chinese/Dim Sum: HK Lounge 1 or 2, dont go anywhere else for dim sum.
Dinner: House of Prime Rib, make a rez now if you like meat.
Neighborhoods to spend time wandering (tpns of retail, bars, restaurants): NOPA/Divisadero, Hayes Valley, Mission, and Downtown.