Got clients who love the outdoors? Get them on a bike, and let them explore New Zealand themselves.

Bikes can be hired to suit any type of cycling, or they can even be purchased on a buy-back scheme from some stores.  
For a fully inclusive experience, clients should take a guided cycle tour where everything is taken care of, including meals and accommodation, gear transportation, bike and safety gear hire.
A good resource for you is Ngā Haerenga, The New Zealand National Cycle Trail. This encompasses 23 Great Rides that stretch the length and the breadth of the North and South Island. Clients can pick rides to suit their ability, or how long they wish to ride for. There are guides available too, so they can choose to go it solo, or get a local expert along who can point out all the must-sees along the way.