If you are looking for an alternative to the usual booze buses in NZ I did a trip with Flying Kiwi (www.flyingkiwi.com
), I had 27 days with them around both islands and can definetly recommend. It was a camping trip, and each day there were heaps of hikes and other activities. Those that were keen on cycling were able to hire bikes also. The camping was often in remote areas so not much good if you are looking for a clubbing trip.