Stayed at the Adelaide on October 25, 2008. Adelaide stands out in three respects:
Location: 2.5 blocks from Union Square and North of Geary Blvd. (read safer particularly walking on Post street to Union Square. It is also not that far from Market Street. Best to walk on Post to Powell (busy) or one block further (Stockton). Within a short walk there is transportation all over the city and East Bay.
Atmosphere: cozy, very intimate/comfortable common area "living room," . Accommodations are typical "hostel" - nothing special. Breakfast is fine, not bad, not particulary good, better than average coffee. Relatively quiet.
Staff: the staff is particularly nice and and helpful. Breakfast was prepared one hour before usual (6AM - possibly for the benefit of guests leaving early). They seem naturally very kind, friendly people. Guests likewise are pleasant.
Even though I am older, I was completely comfortable.
I would highly recommend this hostel for the above reasons.