Originally Posted by
tods27
As noted above, everyone has their own way of valuing miles. I generally start with a trip I want to take, then search for a revenue ticket and a mileage ticket and do whatever comparison I want at that time. Generally I have an idea of what I'm willing to pay for the flights (e.g. $350 to take the trip), and I'm comparing the mileage ticket to that. For international long-haul, I simply look for C redemptions and don't look at what the revenue ticket would cost for C, as I won't ever pay for it. I don't evaluate any of my mileage usage on a straight CPP scale.
As a counterpoint, I compare to what a similar journey would cost
with the same search effort, rather than exact same flights. If I am planning my trip around award space, I compare to a good fare on the market, usually something like $2,000 r/t for the US to Europe for example.