Those flat-bed seats for international business-class fliers? Now that most airlines offer them, they are not so special anymore. Instead, in the newest iteration of the battle for deep-pocketed fliers, the airlines are introducing an ever-growing assortment of in-flight amenities to go with those seats.

Delta Air Lines, in the latest move, plans to announce on Tuesday that a partnership with Westin Hotels and Resorts will give business-class passengers on international and transcontinental flights “Westin Heavenly In-Flight Bedding,” starting this summer.

That follows the introduction in the last two years of upgrades in business-class services by airlines like American Airlines, United Airlines, Virgin Atlantic, Lufthansa, Cathay Pacific and Qantas, featuring everything from improved mood lighting and in-flight entertainment to designer amenity kits and the option to pre-order meals by e-mail.