San Juan is a quiet city in Argentina and is the capital of the San Juan administrative region. It has been completely rebuilt after a recent massive earthquake. It is not as famous or as visited by backpackers as its neighbor: Mendoza, however, it's worth seeing for its new cathedral with its interesting architecture, the natural history museum with the oldest dinosaurs on earth, and to simply stroll the streets. We recommend trying some parillada al fresco (but be ready to have to wait until very late, since the typical restaurants open after 9 or 10 pm).
The local San Juan wines are excellent and very cheap, so go for a winery tour if you get the chance (but avoid the champagne, which was very disappointing for us). You can learn a lot about wine from very friendly wine makers who are proud of their work. San Juan hostels can also serve as a hub to the nearby mountains for fans of the great outdoors, or to the fantastic scenery of the badlands which can be compared to their US counterparts, only much less crowded.
Make sure you pick a hostel in San Juan which is centrally located because public transport is not the best, and the suburbs are very quiet. We also recommend that you choose your hostel in San Juan in advance since some are very quiet and might not be suitable for lively backpackers, or gap year kids wanting to party all night.
When staying in a San Juan hostel, we found that the region is best enjoyed if you have your own transportation, even though getting there is easy by bus.