I think the bottom line is that everybody has to do their own cost/benefit analysis. Some add for the cost of their time, some (who consider it a chance to have some quiet time) would subtract.

If I could ever make it to near top status, the SWU's would be great, but this year, I might not be able to use them for int'l travel because we are having a baby. Any other year, it might be more valuable (well, maybe in 5 years or so, now!)

It also seems to me that, like any good accounting project, there are several *correct* answers. Even if you really like flying business/first to Europe, is the value to you really the difference between the cost of a business ticket and a coach ticket? Maybe it is, but maybe you say, "I would only pay up to $1,000 per ticket for that comfort." Then, the value is $1,000, not the difference that the airline charges.