Well we're flush out of miles at this point, but sometimes there are reasonably good airfares to Santiago. Delta, LAN (an American Airlines partner), and American all fly there with only 1 or two connections from pretty much anywhere in the US.
Also, although Portillo's prices may seem a bit high at first, keep in mind that the price is all-inclusive of 7 days lodging, lift tickets, and meals, and the special fitness and entertainment offerings.
Originally Posted by Portillo website housing page
Prices include seven nights lodging, four meals per day, lift tickets, and free access to all our fitness and entertainment facilities.
They have two lower-cost alternatives to the hotel. The Octagon Lodge holds 4 people so the per-person is less. And they have a ski-dorm facility, the Inca lodge, which is only $600 USD for the week, still including lifts, meals, and event access.