On a different matter - is it better North or South Island?
If you want good scenery, North Island.
If you want GREAT scenery, South Island.
If you want to be warm, move to Australia.
Seriously, I lived in the South Island and loved it. Spectacular mountain ranges and fiords etc. However the population of the SI is much lower, the towns are smaller, therefore there may be better job opportunities in the North Island. In general, the pay in NZ is low, so I don't think I'd be expecting any great salary as a CRM instructor, unless they're in demand.