Also don't forget the opportunity cost of miles, particularly on long distance flights. I generally value miles at something more than 1 cent per mile. I have a trip to Romania, it prices out to around $600 dollars. I can get there using 50,000 UA miles. But if I pay for it, I get to keep those 50,000 miles plus since I get double miles as a prem exec, around 18,000 additional miles. So the question is, would I rather have 68,000 miles or $600. In this case I took the miles.