As you are more than likely to find yourself in several other Chilean or South American cities (and beyond!), I have complied a list of other good options for your journeys outside of Santiago. Although I do try to recommend hostels that I have personally visited, this cannot always be the case. Please do your research before booking one of these hostels. A good source would be Hostelworld.com (where our hostel rates very well!).
This is a list of travel related sites that includes hostel listing sites.