North Island - for sure beautiful, but very inhabited and commercial. If you don´t mind crowds during summer, especially in Auckland region, you will love it. We travelled within North Island during winter and still was quite warm, low on tourits counts and better prices. Get a van with heating and nothing will stop you either
Three weeks were not enough to visit even hot spots, but we saw allmost everything we wanted to see. Our top places - Hot watter beach, Rotoroa region and for sure Tongariro. If you love rollercoaster, try Forgotten World Highway, after 160 km of twisting road I felt really carsick - as a reward you will get amasing wiews of volcano peaks Tongariro and Taranaki. Don´t forget to visit gigantic Kauri trees and go for a fish or sail in Bay of Island.