A few quick notes:

1) I need to check out a few places that are particularly well regarded, like Kauri Cliffs, but in general I'm inclined to mostly agree with Pausanias that the super high end luxury approach may not be the best in New Zealand. We have certainly had as good of or better experience at what amount to high end B&Bs rather than the top tier places that we have tried out. The law of diminishing returns kicks in much earlier in New Zealand than other places, so going high end often involves paying 10x as much money for basically a better hard product and more refined if sometimes less friendly and helpful service.

2) I found Blanket Bay to be particularly disappointing--both in terms of food, which I was looking forward to, and service. It's a really beautiful setting, and I saw other people getting great service, though, so YMMV. At their price point, though, playing favorites with service isn't really acceptable.

3) In Queenstown, I liked the Spire. More of a botique than true high end luxury, but being in town versus having to drive around for most food/drink options can be convenient.

4) There's basically no such thing as "too hot" in New Zealand. February is generally the best month overall for weather; January is probably okay too. In December and March, things will be fine but a lot more uneven.