Carang is right, to really see NZ you need at least 3-4 weeks.
It is a very diverse country. I, for example, would never do Auckland if I only had a week - it's just another city - I would fly straight into Queenstown and do all the attractions of the South Island - hiking, scenic views, bungy jumping or jet boating or eating out at Queenstown's fabulous restaurants in one of the most scenic places on earth.
I might include flying into or out of Queenstown and into or out of Christchurch too, so that you can do the drive between Queenstown and Christchurch (approx 5 hours) which is very scenic in places but takes in some different south Island scenery.
So - what kind of thing do you like to do?
PS - in terms of weather - it depends where you go. Auckland is warmer than anywhere on the South Island; Wellington is very wet and windy - in fact much of NZ is wet.