I go to the US frequently, but am lucky because I have a lot of miles from my working days. I also still apply for any good credit cards that offer mileage rewards. For example, I got the Starwood Amex that offered a 30,000 point bonus. On Starwood, transferring 20,000 points gets you a 5,000 point bonus, so I transferred them to American Airlines. If you have flexibility when you fly, you can find 20,000 mile one-way flights to Buenos Aires. (I just booked one.)
I also switched my money market account to one that gives American Airlines miles on the balance rather than the 1% or so you can get online. Getting miles turns out to be a much better deal!
Keep up on some of the points offers by reading travel blogs. There are some good ones.