In Die Hard 2: Die Harder, NYPD Detective John McClane is picking up his now reconciled wife from her flight in from Los Angles. But he is in Dulles Airport, in Washington DC. When there is five major airports that are closer for John. La Guardia & JFK & Newark, and even Philadelphia or Hartford CT. Why the yippee ki-yay were they going to Dulles?
They were in Dulles because they are visiting Holly's parents who live in Virginia. By Die Hard 2, McClane is no longer NYPD but has moved to LA to be with his family. Presumably he flew out with the kids ahead of Holly who likely had to work, being the ever busy executive.
EXT. DULLES TERMINAL - DAY 1
JOHN MCCLANE, long topcoat FLAPPING, comes running out of the terminal towards an AIRPORT COP in plastic covered uniform who is supervising a TOW TRUCK DRIVER who in turn is manhandling a sedate sedan with Virginia plates and a "GRANDMOTHER ON BOARD" sign on the rear window.
MCCLANE: I'm here, I'm here, false alarm, let's just let her down nice and easy -
COP: Sure. At the impound lot. (POINTING) Next time, read the sign.
MCCLANE: You don't understand, I'm just meeting my wife's-plane - you gotta give me this car back.
COP: Sure. Tomorrow 8 to four, you pay 40 bucks, we give it back.
MCCLANE: This is my mother in law's car. She already hates me because I'm not a dentist. (SHOWING-BADGE) See, I'm a cop. LAPD. How about some team spirit?
COP: I was in LA once. Hated it.
MCCLANE: (going with the flow) I can relate to that. Hate it myself- (turning to tow guy) Hey, that's a plastic fender, Jesus- (back to cop) See, I used to be a New York cop still got my ID somewhere -I only moved 'cause my wife got promoted
From the Die Hard Wiki:
Now reconciled with Holly (who has adopted a hyphenated last name), John is living in Los Angeles and is serving there as a cop. John and the kids are in Washington, D.C., visiting Holly's parents as he awaits the arrival of Holly's plane.
There are several movie reviews that say the same, e.g.
John has actually taken that cop job in L.A. ... [he] is visiting Holly's parents in Washington D.C. and is picking up sweet Holly from the Dulles airport in the hope of making this Christmas one of peace and hope and joy.
We now have Dulles Airport, where on Christmas eve, McClane has found that his car is being towed, and unable to get the car back, McClane calls Holly and convinces her that they need some time alone together since the kids are with Holly’s parents (that is why she is on a plane to Dulles and McClane is in Dulles).
It's Christmas again. Reconciled with his wife Holly (Bonnie Bedelia), John McClane is looking forward to spending a family holiday at her parents' home in Washington, D.C. He's at Dulles to meet her flight when he senses something amiss.