(CNN)There's a new front line in the battle of the airline carriers -- the airport lounge.
From the opulent and exclusive to the innovative and inclusive, lounges are now more than just a place to relax and have a snack before a flight.
With airports ever more crowded, airlines are realizing the importance of improving the whole flying experience.
"The fight is happening on the ground now," says Nicola Lange, director of Lufthansa First Class Services & Lounges.
She says that with in-flight premium experiences becoming more and more similar across airlines, it's increasingly important to stand out on the ground in airports.
It's about "touching the hearts of passengers," says Attila Dogudan, CEO of Turkish Airline's lounge operator Do&Co.
"There is loyalty which you get back from your clients if you treat them like we do."
So who gets it right and how do they do it?
Decades of investment
Some long-established carriers, so-called legacy airlines, have invested in their lounges for decades.
The Virgin Clubhouse in London is often held as a prime example of a lounge that keeps reinventing itself.
And the "Gulf three" -- Emirates, Qatar and Etihad -- have arguably been leading the way with large, luxury lounges that some fliers look forward to visiting.
By comparison, travelers on some U.S. carriers are more likely to experience outdated rooms and minimal features.
Markus Binkert, chief commercial officer for Swiss Airlines, says the lounge must be a lure to customers in itself.
In Zurich, Swiss recently opened a vast new space for its premium and first class passengers -- with separate sections for business and first class, just like in the air.
"When we create lounges we always try to think, 'What will be the one distinctive factor?,'" he says.
"In this lounge it will be the terrace ... this beautiful scenery of the Swiss Alps. It's going to be a destination of its own."
Turkish Airlines flies to more countries than any other airline.
With its expanding fleet and growing route network, it needed a lounge that could cope with its size and reputation.
In 2014 it doubled the size of its flagship CIP lounge in Istanbul to 6,000 square meters, making it one of the world's largest.
The lounge trades heavily on cultural authenticity, offering Turkish food and culture -- there's fresh-prepared pita and baklava plus massage therapists on hand.
Airlines are always willing to offer extras to serious elite travelers, but Lufthansa seems to have one-upped the rest.
In Frankfurt it offers a private, first class terminal.
Upon arrival (via Porsche or Mercedes, naturally), passengers can expect personal assistant, bedrooms and private bathrooms outfitted with large bathtubs.
Lufthansa's Lange says this helps puts her airline ahead of the lounge game.
"Our customers never have to touch the airport directly," she says. "They arrive here, they go through security without lines.
"They can dine, wine, sleep, work. They have a personal assistant who reminds them when it's time to leave so they can really focus on whatever they have to focus on."
While top-end facilities are part of the recipe, for some it's also about exclusivity.
To access Lufthansa's private facilities, travelers must have a first class ticket or be a member of the airline's HON Circle -- a status that requires clocking up 600,000 air miles in two years.
It's not just the airlines that are playing the game.
Many independent lounges are disrupting the industry and expanding access to those who otherwise couldn't get the lounge experience.
They're targeting cost-conscious business travelers who fly economy but still need to find peace and quiet, do some work done and maybe sleep or take a shower.
Lounge by the hour
Plaza Premium, founded 18 years ago by former senior bank vice president Song Hoi-see, now has 130 locations worldwide.
Customers pay by the hour, usually in increments ranging from $35 to $50.
Song refined his concept after struggling to work in air terminals after losing travel perks when he quit his executive bank job to start his own company.
"I ended up stealing electricity in the public area. Can you imagine? It's a very, very uncomfortable experience," he says.
Credit card company American Express is one of the newest players in the independent lounge game.
It's set to open its seventh U.S. location this year.
Its lounges are for its most loyal customers and for those willing to pay.
Alternatively, lounge pass programs give economy-ticket travelers access to both independent and airline lounges worldwide.
The price of this convenience is usually between $20 to $50 a visit.
With increased access and many more people flying, it remains to be seen whether lounges can retain their reputations as oases of calm in hectic airports.
And with the reputation of airlines now also increasingly relying on this product, it should be interesting to watch as they try to deliver on the ground as well as in the air.