You start referring to cities by airport code rather than by name.
CATHRYN I. WANDERS, CEM, EXHIBIT OPERATIONS MANAGER, OPTICAL SOCIETY OF AMERICA, WASHINGTON, D.C.

You start relying on your cellphone knowing which time zone you're in before you do.

You realize that the seats in the lavatory are more comfortable than your assigned seat in coach.
JEWEL E. CRIPE, COURTESY ASSOCIATES, WASHINGTON, D.C.

You're actually relieved that, due to bad weather, you have either missed your connecting flight or that it has been canceled and you get to check in at the airport hotel to order room service for dinner, watch a movie and go to bed.
DAVID WELLINGTON FINCH, CMP, MANAGER, MEETINGS AND TRADE SHOWS, AMGEN, THOUSAND OAKS, CALIF.

You don't go to the movies anymore because they may show the one you want to see on a long flight.

You look forward to the first of the month when the airline magazines change.

Your net worth is higher in terms of frequent flyer miles than your 401K. (How sad is that?)
JOAN ORENTLICHER, CMP, ACS, AVP, MEETINGS & CONVENTIONS, LOMA, ATLANTA

You are shopping in the venue gift shops to bring back the “collectible swap” pins for the airline attendants, since you will see them on the flight back or on your next trip.

You come out of customs for your ground transportation and all of the taxi drivers greet you by name.
MARY-ANN URBANOVICH, MS, CMP, MEETINGS & EVENTS MANAGER, PLANNING FACTORY INTERNATIONAL LLC, WILMINGTON, DEL.