<< Going to be in San Fran for a few days for a conference.
What's there to do & see, recommendations?? >>
Check out the Golden Gate Bridge and Ghiradelli Square and the Cannery, adjacent to Ghiradelli Square. Avoid the rest of Fisherman's Wharf and Pier 39, tourist traps.
Check out Golden Gate Park, at least a drive. The Strybing Arboretum (near the 9th Avenue entrance) is a terrific walk in the park, admission is free.
The Legion of Honor museum is beautiful, it's up in the northwest corner of SF, in Lincoln Park. Lots of folks take wedding pictures there, good view of the Golden Gate Bridge. 
As for cool neighborhoods for restaurants and nightlife, I recommend Union Street (Cow Hollow), Chestnut Street (the Marina), and North Beach (Columbus Street and the Washington Park area).
Have a good time.
-PCM