Apologies. I meant to update by now. Thanks WindFlyer for reminding me.
There was some lobbying for Queenstown and not for my other mainland suggestions, so going with the wishes of FTers with Queenstown.
Both Qantas (one world) and Air NZ (star alliance) fly to Queenstown from both Auckland and Christchurch. So not too hard to get to. Closest sky team gets is Auckland & Christchurch on Korean.
The flight in to Queenstown is especially stunning as weave between the mountains on approach. Good views out both sides, but best on the right. The views on the flight out of Queenstown are okay but not as good as on the way in.
I'll add accommodation info later. As with the rest of New Zealand, major chain hotels are few and far between. However Queenstown is a major tourist spot so there is a wide range of good accommodation ranging from backpackers through to luxury hideaway lodges.