You have to be careful with NZ as population doesnt necassarily mean jobs. Hamilton has 125,000 people and plenty of jobs, but Tauranga with a population of around 100,000 has very few jobs. Some of these places have more population than industry due to being holiday/scenic/retirement spots. I think Aucks, Ham, Welly and ChCh are the only places where there is a good work/population balance.

Touring around is the only way to go if you don't know where you'd like to settle already.