Bruce:
New Zealand doesn't really lay out all that great for a one-week golf trip ... the best courses are spaced pretty far apart around the country, and few of them are in the South Island, which is the most beautiful part of the country.
It is generally accepted that the top five courses in the country today would include Kauri Cliffs, Paraparaumu, Kinloch, and Cape Kidnappers, with some stronger argument about what's the fifth. Those four are all on the North Island, though it would be a +/- ten hour drive from Kauri Cliffs to Paraparaumu. All of them are worth playing more than once, but if you want 3-4 other courses in the same vicinity, you could try Kaitaia up in the far north, Titirangi near Auckland, Wairakei down near Kinloch, and maybe Rotorua for another old-time venue. If you go to the South Island, the only course I've seen that I would recommend is the very quirky Arrowtown course, on the outskirts of Queenstown, which has been written up here.