Disclaimer: Im the Promotions Manager for South America Snow Sessions...so, this is what i do.
It really depends what you are looking for. I am naturally going to recommend Cerro Catedral in Bariloche, because thats where I go in the summer. It's the largest resort in South America in terms of acreage, and has some of the most consistent lift openings in the country. The terrain isnt the rowdiest in South America, but unless you are Hugo or Seth, you won't be missing out on anything that you would find in Lenas or Portillo.
The thing about Bariloche, is that you have a city to come back to in the evenings. Its a lot like Salt Lake City is to the US, except that Argentinians party insanely hard. But there are facilities. Hotels, shopping, hospitals. If you get hurt in Lenas or Portillo, expect a 3 hour heli ride to the nearest x-ray machine.
The other thing about South America, is that you want to go with someone who knows the area, or a group like South America Snow Sessions. The countries are safe, but they love taking advantage of Americans...more so in Chile than Argentina.
I'll shoot you a PM and we can talk more. But for now, check out this video from last season.
Any other questions, feel free to ask me, either in the thread or via PM. Or get ahold of Garrett Russell, our head coach on here. GfunkRussell is his name. There are a ton of kids on NS who have come, and they all loved it.
www.sasnow.com
