Auckland is New Zealand’s main international gateway airport, and many international airlines fly into Auckland (including Air New Zealand, Qantas, Pacific Blue, Jetstar, United Airlines, Emirates, Lufthansa, British Airways, and many other code share arrangements). The main departure points are London, Los Angeles, San Francisco, Buenos Aires, and most major cities in Asia, the Pacific Islands, and Australia.
Auckland airport has two terminals (domestic and international), linked by a shuttle bus or a short walk. Both terminals have all the amenities you would expect of a modern airport, and there are many hotels in the vicinity. There is no rail service to Auckland airport, but there are bus, shuttle, and taxi services available. The journey into Auckland central is at least 30 minutes.
Christchurch is the other main international hub airport. Although smaller than Auckland airport, it also has all the main amenities, and good accommodation options. Like Auckland, bus (#2, #10, and #29), shuttle, and taxi are the only transport available. You can fly direct into Christchurch from the main Australian east coast cities, as well as from Singapore, Tokyo, Osaka, Fiji, and Rarotonga.
As the nation’s capital, and with many connecting flights through it, Wellington is a very busy domestic airport. It has a few shops and a range of eateries. A new international terminal opened in 2010, but due a short runway, larger planes cannot land in Wellington. This means its international services are limited to Australia.
The other main centres all have modern airports with good amenities, but some small towns may have very limited terminals.
The usual airline security is conducted on the main routes, though not always on smaller planes. New Zealand security staff and generally fairly helpful and friendly, but that does not mean they are any less strict about what you can carry on an aircraft.
Short and long term parking is available at all major New Zealand airports, though it can be quite expensive. At the smaller airports, they are usually quite relaxed about private car pick-ups and drop-offs.