San Bruno sits at the geographic dead centre of the Bay Area's transport hub. SFO is two minutes' drive away — almost no other Bay city is closer to the airport.
BART runs to San Bruno station from downtown San Francisco in about 30 minutes (Yellow and Red lines) and on to Millbrae. Caltrain stops at a separate station near downtown, with regular service south to Palo Alto, San Jose, and on to Gilroy.
By car, take Highway 101 north or south, or take I-280 — the more scenic option, running through the wooded ridges west of town.