Beeing nice to the employees helps in many cases (I some times bring "my" local Airline-employees some Swiss chocolate).

One more story: On the Sunday, when Germany played the US in the world-soccer-championship-tournament, IAD was closed because of bad weather for about one and a half hours, which made the last flight to Europe totally overbooked of late coming-in passangers - economy and business on UA to FRA was overfull, the lady at the Red Carpet (I shared some Swiss chocolate with her before), after a short phone-call with the gate, gave me a free double-upgrade from eco to first (because of my status 1K she said).