H Rado Hostel sometimes feels more like a hotel than a Hostel. Very clean with a great common / dining area on the top floor. The breakfast spread is pretty good and the staff are helpful. Nice location too, since it's close to the bus stands, underground station and within walking distance of a lot.
The Hostel is right opposite the entrance to the Universidad San Sebastian, which is a good landmark. The Hostel's location in Barrio Bellavista means plenty of options nearby to eat and drink.
The shuttle service to the airport organised by the Hostel is also really convenient.