On a recent holiday ( July / August 2018 ) we had 3 flights with Air NZ in just under 3 weeks.
We "one-uped" from economy to premium economy from London to LA. It cost us an extra 450 GBP per person, but was well worth the money.
The stewardess introduced herself and knew our names as we sat down. Nothing was too much trouble. The food was great, proper cutlery, real glassware, nice big seats, loads of legroom. A good selection of films on the entertainment system. Once food service was finished they set up a small bar in the galley. You could either help yourself to any of the drinks and snacks or order through your entertainment system and they brought them to you.
Flying from the Cook Islands to Auckland we used the One-up system again to upgrade from premium economy to business class. Only cost 100GBP each
Use of the lounge in the boarding airport..drinks, food, showers,
The seats make up into a lay flat bed if required.
Priority boarding, Champagne whilst the rest of the flight board.
Pre-meal drinks, wines with each course, cheese and port to finish the meal.
We had never flown anything other than economy before, so the one -up system lets you treat yourselves without blowing the budget.