Truthfully, the airlines have to refund full amount if you cancel within 24 hours. I always wait until a few days before and book, print confirmation, then cancel. Hate to say that, but that way I can use my full 600 or 1200 freeplay. I also of course, have my original airfare that I purchase a month or so before. Guess that's kinda cheating, but with all we spend, they should just give the 600/1200!