I stayed at the Green Tortoise in San Fran... not sure about private rooms, I stayed in a room of 4.

The local seems a little seedy when you look around (strip clubs and whatknot) but I never felt unsafe as every club has security and bouncers round the clock. the hostel also has security after a certain time at night, but as long as you're a guest you can come and go (no lockout). the hostel itself was one of the cleanest i've stayed in. they actually cleaned the rooms everyday and the common areas were always picked up. never really had to wait for a bathroom, maybe once- and I was never grossed out by them....

It's located right on the edge of chinatown, so I walked everywhere i needed to go- only taking cabs to get home from the bars at night.

overall I loved it! great staff, fun activities (pub crawl our first night there, met awesome people staying at the hostel along with some stellar locals...), great pizza places and convenience stores right near, walkable distance to clubs, bars, parks, shopping you name it!

hope this helped!

the medjool is expensive but in the mission which is a great neighborhood. I've never seen the rooms, but the rest of the building seems nice and it's relitively new. If you eat in the area, eat somewhere else. Medjool is expensive and they're a millinon great restaurans and Taquerías in the area.
www.medjoolsf.com/elements_home.html