Wanganui Airport (WAG)
Not a ton of flights, but super easy access and will easily get you to Auckland.
Great airport with good cafe for business meetings or a place to have lunch.
Wanganui Airport has that "everything is very convenient feel", for a provincial airport. The Terminal was refreshed in 2007. South Beach Cafe is very nice place to stop for a coffee and the staff are friendly. Hence, I make a regular call on Sunday afternoons to open the historical Airport Control Tower between 2pm - 4.30pm, with other enthusiastic volunteers.
There is quite a cluster group of Aviation businesses and clubs nearby.
Air Wanganui Wgi to where you want
Air New Zealand Wgi to Auckland
Sounds Air Wgi to Wellington Blenheim Nelson
and others including Aero Works.
Wanganui Aero Club
not forgetting Airport Control Tower Restoration Group, Air Cadets, Aero Modellers Club.