Try the Mitai dinner/show in Rotorua for an evening that's touristy but genuine.  There's plenty to eat but bring cash for alcoholic drinks.  Performers are the "real deal."  The owner explained that his show provides a way to assure the Maori culture and history goes on to the current generation.  It's an educational as well as colorful and entertaining evening.

 Here are a few links to a variety of information about the culture and heritage of New Zealand.

Maori Culture

New Zealand's proud musical heritage

Culture Introduction - NZ

Haka - NZ

NZ History Online : Culture and Society

Hangi - traditional Maori food

Pounamu (greenstone)

Pounamu is to be bought as a gift, never bought for youself.