Having just done my AOW - admittedly not in NZ - all i can say is get an instructor who is enthusiastic about what they are doing and you will have a great time. If they're only there for a job or the money then it'll be the usual in/out and sign off your log book.
The best piece of advice I got was to ask the instructor what they like to do and base your choice of AOW dives around this - if they're enjoying themselves, then so will you
Ours loved the environment and wildlife, so we did the fish ID/boat/PPB and had a great time
If you're in a club or with other divers then ask around to see who they recommend. I've been very lucky to have my hand held (sometimes literally !
) by some great divers and I've found them all to be really supportive in helping out us newbies in gaining experience. I have now been very lucky in finding the best instructor and will be using him for as long as he'll put up with me !
I know most of them read this website, so thanks guys you've given me some great memories