Heaps of great walks in NZ - refer to the doc web site for info. The New Zealanders generally leave the Great Walks to foreigners but there's lots of other stuff to do.
I went up Greenstone and down Caples Valley summer before last - very nice easy walk out of Glenorchy near Wanaka. Also walked up Rock Burn and down North Route Burn - no huts so we took tents. Some do it with just rock bivies but I'd recommend a tent.
As a general rule nobody except Australians take tents walking in NZ if there are huts.
I'd support what Kieran says about river crossings. Crossing rivers in NZ is an easy way to die. They can carry an awful lot of water, and look benign because they're so clear.