This is me up treble cone last season. Shame my gf cropped the photo coz otherwise you'd see just how awesome the view is, loads of lakes and mountains. I mean, that day right there was probably the most awesome views I've ever seen and yes I have been out of NZ.
As for park skiing, Cardrona has 2 HUGE halfpipes and plenty of everything else... my local is Turoa/Whakapapa (pron "fuckapapa"), they take their parks pretty serious too so it's all good.
For visitors though, you MUST go to Queenstown, Wanaka and most of all Cardrona.
If you're only in the North Island, Turoa's ski village/town is called Ohakune and it's quite hard party :p