The Value of a Mile

...In fact, we used to routinely recommend that program members use 2¢ a mile as a rule-of-thumb target value for their frequent-flier miles, based on the fact that the average domestic ticket price was in the neighborhood of $500 (2¢ = $500/25,000 miles).

Unfortunately, that advice is outdated. In the current environment—with today's combination of sluggish demand and intense downward pricing pressure exerted by the low-cost carriers—the average price of a domestic ticket has fallen below $400. That alone depresses the theoretical value of a mile to less than 1.6¢....

http://frequentflyer.oag.com/stories..._of_a_Mile.asp