It is situated in an old hotel in Nob Hill. I stayed in a six-bed dormitory (bunk beds) with each room having its own private bathroom. The people were nice and the roommates were awesome. There are local tours offered, but nothing you couldn't do yourself with the city transportation pass. They do have amazing day and camping trips to whitewater raft, tour Napa Valley and other regions. It's close to everything. Union Square is barely a five-minute walk and Chinatown is even closer. It's just around the corner from a cable car that can take you to Fisherman's Wharf or Union Square (which will hook you up to the underground metro and bus that is also included in the pass). The hostel offers high-speed internet (20min/$1) and all you can eat breakfast pancakes and waffles. It's a friendly place with daily maintenance. Staff stay for free (minimum of five-day stay).
http://www.usahostels.com/sf/sf-index.html