I went to NZ in April last year. Fell in love with the place
Warning: Franz Josef is HIGHLY expensive. Everything is overpriced here and i mean everything. Hotels are the cheapest thing there actually. I booked before leaving but really depends on season.
With that said, the glaciers are beautiful, but if you're on a budget then you'll only want a night or two here.
We took a helicopter up to the glacier and it was spectacular. Weather can be bad though, our helicopter was delayed by over 24 hours.
I havent read all this thread so unsure where you are heading, but we did north and south island in 2 weeks, hitting most of the tourist traps.
Skipped Queenstown for Wanaka as the scenery is just as good and its a (slightly) quieter place.
All in all my fave place was Kaikoura, then Wanaka.
Not sure if your hitting the north island, but if so, dont miss the big volcanoes in Tongariro National Park - my other half decided it would be wise to drive up one (or was it another mountain, i cant remember) in heavy fog, hundreds of metres off the ground, slippery road and inches from the edge.. needless to say i cant recommend that, but viewing the volcanoes from a safe distance is a MUST - most Aussies will never see mountains like these, they are just huge.
The great thing about NZ is that no matter where you go, you'll always see spectacular sights.. I could spend years travelling that country and never get bored.
Have fun!