I'm UA Premier with no upgrades left in the bank. My wife and I are flying IAD-BRU on Christmas Day, and AMS-IAD on New Year's Eve (currently sitting in E+ on cheap tickets).
According to ual.com, the economy cabins on both flights are almost full, but biz is practically empty.
I'd like to weasel an operational upgrade at the airport (it is Christmas ya know!) Is my best bet to inquire at the check-in desk, or with the agent at the gate. Certainly I'll wear a sportcoat to look the part, but any thoughts on what I can do to maximize my chances of an upgrade?