I can also recommend Tauranga, Raglan and Pauanui Beach, all coastal and very scenic.
Tauranga is not that busy, ATC are as mentioned very nice people and are very patient on the whole unless obviously you are blocking the dash 8's arrival/departure etc, all of the arrivals are easy with good features to follow, the museum there does some good food and also very interesting to look around.
Raglan I found a bit hairy in a c150, the trees at the end of the runway seem very tall! But its fine, think I must have had too many chips in town!
I found Ardmore to be very busy too, it says in the AIP that it is the busiest GA field in NZ and I can confirm this, but again its easy if your on the ball and again have some nice aircraft there.