I stayed in an amazing 3beds private room, with a view to Moika river. In the hostel there is a very nice kitchen, computers and wi-fi, free international phone calls. Very good facilites!
I stayed in a 10 beds dorm. It was too small for 10 people, there wasn't room even for the luggage. It is very good located, close to a metro station and in a walking distance to Kremlim and Red Square.
I stayed in a 6 beds dorm. There was like a living room on it and also refrigerator and microwave. Very pratical.
I stayed in a nice 3 beds private room. It's relatively close to metro and to Acropoles, close to a lot of nice restaurants.