I agree with sdsearch's conclusion that it "seems today that half the airlines only allow upgrades from "not so discounted" fares, and the other half that alow them from discounted fares have ever-escalating "co-pays" that are required to use the miles for upgrades" and that "mile upgrades are getting less valuable" . This is a definite trend. Upgrading with miles used to be a very attractive option in the past but now in most cases it just does not seem to be good value.