This summer, while traveling from New York to Denver, Marc Stewart noticed that the Delta Air Lines terminal at La Guardia Airport felt unfamiliar.

“Usually, I fly United, which means you are in the old concourse where there are not even enough bathrooms. So, I was pleasantly surprised when I walked into Delta’s terminal at La Guardia and saw some innovative options,” said Mr. Stewart, 45, a television journalist. “As soon as you go past security, you see a food setup that’s reminiscent of Whole Foods. There’s a food bar, snacks beyond potato chips. It is a completely different feeling.”

What Mr. Stewart encountered is going on all over the world. Airport operators are updating aging terminals and constructing new ones, wooing travelers with retail and dining options that encourage them to spend more money. And they are spending as much as 30 percent more at some airports, according to OTG, the airport concessionaire that worked with Delta on the remodeled terminal that Mr. Stewart visited.

When revenue from airport amenities goes up, the fees airlines pay to use an airport can go down, which in turn can attract more airlines to offer service to the region.