Even the panhandlers, who are everywhere, seem to be more cheerful than in other cities. The weather helped. For big city people, San Franciscans are amazingly civil, tolerant and considerate. It's the only city I know where drivers actually give the right of way to pedestrians. The setting between the bay and ocean is lovely.
Neighborhoods are interesting and mostly good looking.
And, lastly, the restaurant scene is extraordinary. Walk along Fillmore, Polk, Union, 24th, Lower Haight and Chestnut streets, then explore neighborhoods like Pacific Heights, downtown, North Beach, The Mission and Chinatown. Spend time in Golden Gate Park and along the western coast. I don't usually recommend hotels but the Miyako Inn in Japantown was very good. Ask for a corner room.