Bariloche or the area around San Martin de Los Andes is a beautiful part of Argentina it reminds me of Scotland.
It is also a good idea to take an overnight "coche cama" bus service from BA to that area as it is a lot cheaper than flying and very comfortable indeed - akin to Business class on an airline - big reclining seats with food and drink as well as entertainment all included in the price.^

http://www.viabariloche.com.ar/english/servicios.html