I used a NW award to fly LAX-PTY-EZE earlier this year. It is a bit of a pain to book, but the flight's not too bad. I considered it a bargain of 70k miles for Biz class. I wish there were an easier way to do IAH-GRU-EZE. I've never flown DL Biz class, since they'll start to fly to EZE in December, that could be an interesting option.