If you're staying at Hotel Zelos, take the Muni F line at Market St and 4th St. These are the vintage streetcars that run up and down Market St, NOT the "trolley cars." This route will take ~15 minutes.
Take it heading west towards Castro for 5 stops, get off at the Market & Larkin stop, then walk two blocks north on Larkin Street. City Hall will be ahead on your left, and we will meet on the steps out front at 2:30pm.
For anyone else, take a cab/Lyft/Uber to City Hall's main entry on Polk Street.