Which makes it so peculiar that the German airline waited until last week to launch premium economy, the fastest-growing upscale cabin in the global skies.

Lufthansa hasn't been alone in slow walking its way to premium economy, however. Singapore Airlines, another carrier with a global reputation for top-notch service, doesn't launch its version of the service until next year.

But now that Singapore Air is committed and Lufthansa is all in — more than 100 of its aircraft will have the better-than-coach service by next summer — the rise of international premium economy is nearly complete. After starting as a curiosity 20 years ago, then becoming a niche product, premium economy now has an undeniable place in the international travel firmament.

Business travelers who can't justify or aren't allowed by corporate policy to book business class will pay the premium over traditional coach for more spacious and comfortable seats, better meals and on-the-ground perks. There's also an identifiable core of leisure fliers who'll pony up for premium economy rather than squeeze into the today's dreary coach cabins.

What's surprising is how surprised the airline industry has been by the rise of premium economy. They apparently forgot that business class started the same way 40 years ago. Disillusioned by the high price of first class, business travelers headed to coach only to be lured back up front by the initial business classes, then a service that looked a lot like today's premium economy cabins. As business classes became more lavish and essentially replaced first class, the gap between business fares and coach prices grew so enormous that fliers once again yearned for a comfortable and comfortably priced middle ground.

Lufthansa's new premium economy and the premium-economy section sold by Cathay Pacific of Hong Kong fill the bill admirably and are the standards against which other "fourth classes" are measured. I've flown both recently and can attest to their value and comfort. Will you want to bust down from business class to fly them? Of course not. But are they worth the few hundreds dollars surcharge to get out of coach? Absolutely.

Cathay's premium economy seats boast 38 inches of legroom compared to the industry standard of 31 inches in coach. At 19.3 inches across, the chairs are as much as two inches wider than some coach seats. On the long transpacific hauls from Hong Kong to Cathay's U.S. gateways (Los Angeles, San Francisco, Chicago, Newark and New York's Kennedy Airport) that extra space makes the difference between a civilized flight and an endurance run.

Cathay's in-flight atmosphere is civilized, with 10.6-inch monitors, plenty of in-flight entertainment, at-seat power and USB ports, wider armrests and more commodious tray tables. You receive an attractive amenity kit created by Goods of Desire, a trendy Hong Kong brand. Flight attendants are omnipresent, keeping you hydrated throughout the flight. Meal service is notably better than coach, too.

There are also unique perks on the ground, including dedicated check-in counters, priority boarding before coach customers and increased checked baggage allowance. The price for all of the extras? Between San Francisco and Hong Kong, Cathay's premium economy roundtrip currently sells for $1,944 roundtrip, less a third of the price of business class.

Lufthansa's new premium economy is something of a transatlantic mirror of Cathay's service. It debuted Oct. 8 on flights between Frankfurt and Washington's Dulles Airport and will be on more U.S. routes to Germany by December. I was especially impressed with the upgrades Lufthansa made in the meal service compared to coach. And that's saying something since I generally abhor in-flight food. The beef entree was aggressively spiced and the pasta dish was cannily made with a gutsy shape (garganelli) that holds up well under difficult airline conditions.

While Cathay and Lufthansa may be the carriers to beat in premium economy, there are notable outliers among international competitors.

Open Skies, the British Airways subsidiary that only flies between the New York and Paris, continues to offer the best premium economy experience. It's not as lavish as when it launched in 2008, but the current "prem plus" section offers 20-inch wide seats configured with 47 inches of legroom. Even better, there are no middle seats on Open Skies' narrowbody Boeing 757s. Best of all are the prices. Book far enough in advance and travel midweek and roundtrips are as little as $1,349, the best premium class bargain in the skies.

Open Skies' presence on the crucial New York-Paris route has forced Air France to make its premium economy better than average. Its noticeable upgrades: 12-inch monitors and "shell" seats that ensure a flier in front of you doesn't recline into your personal space.

Also worth noting: The so-called Spaceseat on some Air New Zealand flights. Laid out 2x2x2 on Boeing 777-300s, Air New Zealand's seats are 20 inches wide with 42 inches of legroom. They are also a surprising color (white) and angled in cocoon-like shells. Air New Zealand promotes the center pair as "designed for couples, so you can relax together, or turn to face each other to share a meal."

But Air New Zealand hasn't installed Spaceseats on its recently delivered Boeing 787 Dreamliners. Apparently, the chairs are a little too cutting edge for most travelers. The Dreamliner's premium economy cabin uses more familiar chairs, but are almost as roomy.

Too much room is what doomed premium economy on Turkish Airlines, however. Its so-called Comfort Class on Boeing 777-300s offers 46 inches of legroom and chairs that are 19.5 inches wide. But new aircraft being delivered to Turkish don't have a premium economy cabins and the airline will gradually discontinue premium economy altogether. The reason? Premium-economy seats haven't been selling well enough at a high enough price to justify the abnormally large space that Turkish carved out for them.

And for all of its omnipresence on major carriers flying international routes to and from the United States, Cathay Pacific's general manager of product Toby Smith says premium economy is a harder sell elsewhere.