Flights to Rotorua can be a convoluted process at times. Especially when you look at flying in from destinations outside of the main centers. This has the added effect of making flights relatively expensive. Not quite what you want to hear is it?
Daily domestic flights to Rotorua are carried out, in the main, by Air New Zealand. You can fly in from Auckland, Wellington, Christchurch and Queenstown via Christchurch.
We do have one other service and that is Sunair (The Big, Little Airline), a small family owned aviation company based in Tauranga. Try them out if you're wanting to fly to/from Gisborne or Napier.
It really pays to pick your times. For instance, school holidays bump the ticket prices up massively.
New Zealand has a choice of six international airports.
You need to be aware though that the majority have limited overseas destinations. I have noted the major connecting cities that apply to each airport.
If you click each airport link you will be taken to the info pages on their websites, alternatively, find the best deals on TripAdvisor.
Enjoy your flight.