Originally Posted by 3Cforme

DL's upgrades to Z (Asia/Europe) can be confirmed at time of ticket purchase for PMUs or upgrades with miles, but waitlisting is common. Your point about AA's relative generosity in permitting upgrades on cheap coach fares has merit, but omits AA's copay requirement. DL's upgrades on flights with domestic first rather than international business service are free (and sticker-less) to bottom+middle-tier elites, a perk AA doesn't offer.