Originally Posted by
czpdx
I, for one, would never buy the instant upgrade fare if I didn't see the U - too much of a gamble (and usually an expensive one at that).
I have actually had fairly good luck buying instant upgrade fares when U is not available at the time of purchase. With the routes I fly, U is almost never available at the time of purchase (I was able to use only one of my gold upgrade certificates last year - and that was a ticket purchased 6 months in advance).
If the upgradeable fare does not cost much more, I am willing to take the gamble, so that if and when U space opens at some point, I will get a surprise email that my upgrade has cleared.
But there is a limit to how much I am willing to gamble, and I consider both how full the flight is when I buy my ticket and my guess on how full it will eventually be, and whether I might get upgraded on at least one segment. And I remember that it is a gamble!