The airline's route planners were still working on where they would like the planes to fly, which will determine the aircraft type and its configuration.
Non-stop flights to cities such as New York or Sao Paulo are on the airline's radar.
"A big part of this conversation is working out where do you want to go to over the next 10 to 15 years and to look at it connecting Australians through New Zealand to the East Coast of North and South America."
The airline also was investigating connecting Asia, through Auckland, to South America.
The Boeing 777-200 first joined Air New Zealand in 2005 and its eight-strong fleet of the aircraft has an average age of 11.7 years.
"It's quite exciting because you don't get to replace a key part of your widebody fleet all the time," he said.
"Having said that we've got very good at going through this process and one of the real strengths of Air New Zealand is that we have been able to purchase the right aircraft for the right mission."
The Airbus A350XWB has a long-range variant which is capable of flying between Singapore and New York, a distance of 15,323km.
Boeing's 777X is still being developed and its 8-series could fly up to 16,000km.
The distance from Auckland to New York is 14,185km.
Stretched versions of the A350 and Dreamliner can carry more passengers than earlier models but don't have the same range.
Luxon said the process was a long one but the airline needed to "deeply understand" the pros and cons of each aircraft; how much fuel they burned, how many passengers they could carry and what the mix of premium and economy seating would be.
The new fleet represents a massive capital investment of well over $1 billion.
"It's certainly a lot of money so it's an important decision to get right," said Luxon.
