This topic has been beaten to death before, but the short version is: I know that I wouldn't pay $8,000 for a first class ticket, when I could pay $800 for a coach ticket on the same plane. Therefore, 100K miles is not worth that much to me. A more accurate assessment is based on how much you'd have to pay for tickets to accrue that many miles, and people a lot smarter than me have computed that to be $.02-$.025 per mile.