As the only major sports team playing in urban San Francisco, the Giants enjoy special support among locals. AT&T park (its 3rd name since opening in 2000 when the Giants left the now 49ers-only Candlestick Park) is a relatively small open-air stadium providing nice views of the bay and not much protection from the wind.
With 43,000 seats, games often sell out - order tickets beforehand if you don't want to scalp. MUNI runs directly to the park and offers additional service on game days. Caltrain provides similar service to and from the peninsula.
Address: 24 Willie Mays Plaza, SF, CA
Website: http://sanfrancisco.giants.mlb.com/ticketing/singlegame.jsp?c_id=sf
Wikipedia: http://en.wikipedia.org/wiki/AT&T_Park