Big Mal, I was born and raised in San Francisco (Sunset District) and know it damn well. I don't know if you have the time to travel around as well as get some training in but I do suggest the following:
a. The ferry boat ride from the San Francisco Ferry Bldg to Larkspur Landing in Marin County. Nice way to see the bay adn the GG Bridge, Alcatraz and the small waterfront communities along the route.
b. Lunch at Fisherman's Wharf. (Sabella's is good but anyone you choose will be fine).
c. A cable car ride to the end of the route and back. Used to cost a dime but now it's AA $5 each way.
d. A trip over the GG Bridge to Sausalito and onward to Tiburon with a stop for lunch.
e. Acccept Tbombz invite and let him show you around. SF is worth seeing if you know where to go and TBombz more than likely knows it as well as I do myself. It's prbably the best city in the entire US of A for sightseeing and having a great time if you know where to go and where to look.
f. Visit Muir Woods in Marin County.
g. A session at Gold's on Upper Market near the Castro neighborhood to see what that section of SF is really all about. Expect to see some damn good bodybuilders there and things that may shock the shit out of you.
h. A beer or two at the Top of the Mark. (Just ask and someone will point you to it.)
i. Ride the Bart and see the city like a native.
Born and raised there myself...currently typing 5min south of SF.
As far as the Gold's in the Castro? The 9th & Brannan gym is far better. Better equipment, people, more space, parking, and better members. And for the freak factor that you threw in as well, yeah they have that too.