Take a gander at the Charles M. Holmes Campus at the Center (1800 Market St; 415-865-5555), San Francisco's gay community center. All manner of meetings, gatherings, and events of interest to the LGBT community happen here.
San Francisco's most widely read gay newspapers are the biweekly San Francisco Bay Times (415-626-0260) and the weekly Bay Area Reporter (415-861-5019). The Bay Times tends to be comprehensive in its coverage and scope, while the BAR is oriented toward gay men. For clubland briefings, check out Gloss Magazine (510-451-2090). All of the above are readily available for free in the Castro.
The San Francisco Bay Guardian (415-255-3100; www.sfbg.com) and the SF Weekly (415-536-8100) are free city weeklies with in-depth coverage of the political and entertainment scene, and a solid resource for sightseeing and entertainment. You can get general tourist information from the San Francisco Convention and Visitors Bureau (415-974-6900), which has a Visitors Center, on the corner of Market and Powell, open weekdays from 9 a.m.-5:30 p.m., on weekends 9 a.m.-3 p.m., and 9 a.m.-1 p.m. on major holidays. You can request information or make hotel reservations on the bureau's website.
The Women's Building (3543 18th St; 415-431-1180) is a resource center for local lesbian and feminist organizations. Its exterior is covered with the gorgeously vivid Maestrapeace mural, painted by a group of women artists, including the well-known Juana Alicia. CastroOnline maintains a calendar of events and links to gay bars, restaurants, bars, and clubs in the Castro and beyond.
If you'll be using mass transit, a MUNI Passport is your best option, at $24/week, $18/3 days and $11/day. The passes allow unlimited use of MUNI buses, trains and cable cars (bus, streetcar, and BART rides within San Francisco cost $1.50 per ride; cable car rides run $5, or $3.50 plus a valid token coupon). You can buy a MUNI Passport at the Powell/Market cable car turnaround. You'll find the San Francisco Street & Transit Map at most book and souvenir stores. Another invaluable reference is the San Francisco 3-1-1 Customer Service Center line, at (wait for it) 311.
If you're flying into or out of SFO, check www.flysfo.com for flight information, a ground transportation summary, weather information, maps, and more.