I have heard from International Friends that the Green Card is the best way to go.

I can also tell you that many millennial consumers I know are big fans of American Express Cards. Gold, Green, Platinum, Blue. Nearly every millennial who I know has at least one Amex in her/his wallet. I wonder if the Amex Travel credit they are doing this year could serve as a substitute in the future for the Airline Credit. Some may consider it a downgrade, but honestly I would consider it a win.... It is very easy to track and use and it is clear where it will work, and where it will not. No more buying ticket at just the right price or manipulating gift card and payment purchases in the perfect way to hope and pray the credit works. No more a nicer seat works with this airline but not with that one.