From my limited experience LAN is kind of stingy with the award tickets they release. For example I found out from the AA CSR who talked to the LAN liasson that there is no award inventory available for AEP-BRC flights. To get to the prime tourist spots such as Bariloche you have to pay to the tune of just under US$ 300 r/t. One bright spot is that I was able to grab a flight to Pto. Iguazu as an award but the availability was very limited.