If you're going to South America, American Airlines and its partners have a large part of the market, and I'd focus on them. For a credit card, I'd get a Starwood American Express card if you're dedicated to earning miles. If you also get a Citibank Visa card for the places that don't take Amex, you'll fill out the miles earnings possibilities. If you combine the three and use them for several years, it'll be relatively easy to get elite status on AA. Of course it helps to pursue all the other miles earning opportunities, like those on pgary's website.