Airlines That Allow Double Upgrading?
 

I'm curious to know which (if any) airlines allow Double Upgrading, either at the time of resevation or on a standby basis.

On United it's no on both counts (except when you get a very accommidating agent), and it frustrates some of us that have coupons/miles to burn to only be allowed a one-class upgrade.

I understand United's reasons for this from an economic point of view as well as the operational challenges of last minute musical chairs at the gate when time is of the essence. But I was wondering if any of the other majors have this as part of their programs?

Thanks.