The Ferry Building is a fun place to see. There are cute shops and some restaurants. You could also catch the ferry to Sausalito for a pretty water view of the city. A walk along the Embarcadero is always a good way to enjoy San Francisco.
Top of the Mark is a great place for a drink with a view.
San Francisco's Chinatown is supposed to be the oldest in North America. Some tips for exploring: https://www.inside-guide-to-san-francisco-tourism.com/chinatown-san-francisco.html