I just came back from a whirlwind 2-week trip to NZ, and spent the last 4 nights of my trip at the Puketiti Lodge in Mangonui. This place is run by a wonderful Kiwi-German lady named Siggi. She designed the lodge herself, and is very helpful and knowledgeable about all the things that you can do in the Far North, because she has done them all herself!
The accommodation itself is luxurious, super clean, and surprisingly affordable. It's set among hundreds of acres of olive groves. It has 3 suites, plus a 4th "great" room that can accommodate a large family or a group of backpackers. Each room is spacious, and has a to-die-for view over the Mangonui Harbor. In addition, there's a huge sunny deck for entertainment and BBQ; a common kitchen area; a lounge area; and a study for high-speed internet and phone access.
I really enjoyed my stay there, and would highly recommend this place to anyone who is planning to visit the Doubtless Bay/Cape Reinga area. For the price, you won't find a better bargain anywhere in the area.