Originally Posted by
Sez_Who
For DL intl, you only have a couple possibilities for the UG. One is an op-up, somewhat rare but they do happen if Y is oversold. Your other option is purchase at least an M fare and upgrade with miles.
Flying on a T fare will not impress them, despite your DYKWIA credentials. DL is pretty tough on intl upgrades.
Depending on how much lead time is required you could buy up to an I-fare (discounted business) if you have the time left to cover advance (I think you need 30 day or 60-day advance purchase - can't recall) and are willing to do Saturday night stay-over. Then no need for UG -> and I fares aren't too far different price-wise from M fares.