Wanaka is nice, like the queenstown but not as commercial. I went with fat tyre and did a big day out with 4×4 assist, weather wasn't good enough for heli biking. Good days riding recommended .Queenstown does/did have downhill course next to the cable car…
Rented bikes in Taupo, that was ace nice riding.
Bike rental was variable, some places I got nice new full susses. But I did more than one black run on an 80mm hardtail with v brakes. Entertaining for a little while but not more than a few hours.
I met a guy off here, paul of essence cycles in Wellington. Proper niche (I laughed when I met him as he fitted a fair few stereotypes) singlespeed steel something or other. Lent me a bike and took me fo ride in the pouring rain.
http://www.fat-tyre.co.nz/
and
essence has closed up (in frustration?) http://www.vorb.org.nz/essence-bicycles-closing-down-t101169.html