We are starting in Christchurch and we have a month to explore and finish in Aukland. Not sure of the best route or even what the must sees are....
South Island: Queenstown, Milford or Doubtful Sound, both glaciers and pancake rocks on west coast, Nelson area wineries, Kaikoura whale watching (if you never saw whales before)
North Island: Napier, Rotorua area (do as much thermal valleys as you can - all are different and amazing), lake Taupo, Hamilton gardens, Waikato glowworm caves, Hot Water beach (unique, have or rent shovels to dig your personal jacuzzi during low tide - don't forget to check tides schedule online) and Cathedral Cove nearby (perhaps most impressive wild beach in the world) on Coromandel peninsula; go north of Auckland to Bay of Islands for sail through hole in rock via Matakana area (Omaha beach is for rich and famous NZders), see Kauri tree on the way. Love NZ! about 9 years ago