Luxury air travel within the United States has long paled in comparison with the over-the-top cabins more common on international routes.
But U.S. airlines are souping up the front of their planes with lie-flat seats, an attempt to entice more high-paying domestic business travelers aboard.
Delta Air Lines on Monday said next year it will expand its Delta One cabin, which includes lie-flat seats that are more common on long-haul international flights. Starting in April, Delta will fly the cabin on certain flights from Boston to Los Angeles, from New York (John F. Kennedy International Airport) to San Diego and Seattle, and starting in May from JFK to Las Vegas.
The expansion follows competition from JetBlue, which will add its premium Mint cabin to similar routes next year.
Delta has added a perk for very frequent flyers, those with Medallion status: unlimited upgrades to Delta One cabins around the country, starting in April.
The catch: The upgrades are only available on the day of departure.
Delta's chief executive has been vocal about the airline's efforts to sell more premium-class seats instead of giving them away for free through upgrades.
Delta used to sell about 15 percent of its first-class seats and now between 50 and 60 percent is sold, Delta's CEO Ed Bastian told reporters last month.
"Any business where you give the majority of your best product away, it doesn't work," he said a month earlier at a conference.
The Delta One cabin will become the top offering on some of these routes. That shows Delta is not abandoning free upgrades for its most loyal — and lucrative — flyers, but it is allowing other passengers willing to pay for a seat more time to do so before handing out those seats for free.
Keeping seats open for sale until the last minute could prove lucrative for Delta. Both premium-class and economy-class tickets for travel less than seven days away are about 25 percent more expensive compared with tickets that are purchased two weeks ahead of travel, according to a recent report by corporate expense management company Concur.
At the same time Delta is vying for those business travelers, it won't offer business class on some trans-Atlantic routes next year.
The top offering on flights between Minneapolis or JFK and Keflavik Airport in Iceland, between JFK and Shannon, Ireland, and from JFK to Sao Miguel in the Azores will be Delta Premium Select, the airline's first premium economy class, which offers passengers more legroom, an amenities kit and a bigger seat-back screen compared with regular economy.
Even though the airline isn't offering business class, prepare to pay up for the front of the plane. A round-trip ticket from New York to Iceland in early June in Delta Premium Select is $2,165, a recent search showed, while a seat in regular economy is $570.
WATCH: Delta CEO says his airline has the most first-class seats
