Air NZ is good for intercontinental flights, but otherwise a frustrating experience for *G. No free checked luggage even for *G, no mileage earning in run-of-the-mill booking classes.

This is why I flew Jetstar within New Zealand. Jetstar also offered an attractive "Plus Bundle" that waived any change fees (!) and also included free checked baggage, free seat reservation (I really enjoyed the view) and some funds to spend onbaord for food&drinks. It is a no-brainer. Avoid NZ unless you fly intercontinental.