My prefered drink of choice airside is geographically dependent and is only marginally time dependent:

If I'm in:

CVG CRC - Woodford Reserve on the rocks - a really good bourbon
ATL CRC - Maker's Mark on the rocks or their "Big Apple" signature cocktail
DTW WC - Bloody Mary - (one of the best I've had - Major Peters Bold&Spicy mix, with a twist of lime - yum!)
LAX CRC - Bloody Mary - bartender there makes 'em RIGHT! (horseradish, bitters, etc.) be sure to mention that you heard they make a great Bloody Mary
SLC CRC - Fat Tire beer
HNL CRC - who cares, I'm in HNL!
NRT WC - Kirin beer (from the automatic machine!)

Elsewhere, or if those are not available, I tend to stick with red wine or a local beer, if available.