Jon:
If you go to Kauri Cliffs, definitely go to Kaitaia.
I haven't been there myself, unfortunately. It's a very low-maintenance links near the south end of Ninety Mile Beach, about an hour from Kauri Cliffs. Years ago I wrote in The Confidential Guide that I would give "brownie points" to anyone who ventured up to see it, and a couple of years later I got a letter demanding brownie points from ...
the esteemed founder of this site, Mr. Ran Morrissett. That was the first I'd heard of him. He said Kaitaia was very cool, but of course no one has been there to call him on it.
The coolest "off the beaten track" course I saw over there was a muni links down in Dunedin named Chisholm Park, but that's a long way from the others listed. (It's about like telling you to check out Cabo del Sol while you're in California; except that a green fee at Cabo would probably buy you an annual pass at Chisholm Park.)