Our trip was 17 days, South Island only as our focus was on hiking. We flew into Christchurch and out of Queenstown, on flights from and to Australia. We booked the trans-Pacific flights on Qantas with our Alaska miles and British airways miles. We lucked into first class tickets on the outbound flight.
If you fly direct to New Zealand from the US (LAX), you may end up in Auckland so the suggestion to spend a few days on the North Island is a good one. Maybe work your way down to Wellington, turn in the rental car, and fly to the South Island.
We did a mix of train, plane, rental car, and the 5-day Milford Track trek. Starting at Christchurch, we took the TransCoastal train up to Picton, and caught a water taxi out to Lochmara Lodge for 2 nights. We walked part of the Queen Charlotte Track from there. One can also bring bikes and cycle on this track. The lodge has kayaks for free use, and is in a lovely location.
The train is not currently running due to track damage from the most recent earthquake, but it is cheduled to be back in service in 2019.
From Picton we traveled by bus to Nelson for a visit to Abel Tasman National Park. We booked a day with bus to the park, boat trip with drop-off, and 10 mile walk back to the bus pick-up point, all with Wilson’s. They also do multi-day trips with overnight in their lodges. These are not Maori-owned; the Wilson family are descendants of European settlers who farmed the area starting in the 1850”s.
The day walking on the Abel Tasman track was our least favorite of the trip. I think it would be a great place to go sea kayaking for one or more days, but I could not recommend it for a multi-day walking trip. The scenery and flora do not come close to compare with the beauty, variety, and interest of the Milford Track. I am a botanist and can only describe the plants we saw as scruffy. And there were possum traps every 20 yards or so. Yes, d there are the famed golden sand beaches, and we stopped and swam at one. But they are no more beautiful than our own West coast beaches in Washington, Oregon, and northern California. My husband asked why we had come so far to see beaches inferior to what we have at home.
From Nelson we flew back to Christchurch and picked up our rental car, which we had for one week. We went to Lake Tekapo (beautiful turquoise water, nice hiking and mountain biking) Mt. Cook Aoraki National Park ( a fantastic hike with 2200 steps), Dunedin (university and botanical garden), Clyde (biking the Otago Rail Trail) and ended at Queenstown where we turned in the car.
Queenstown is Adventure Central. Zorbing, zip lines, burgee jumping, etc. It is the take-off point for the Ultimate Hikes guided trips on the Milford and Routeburne Tracks. We did not spend extra times there, but you could if you wish to try some of the adventure sports.
What we did not do is visit the west coast or the glaciers (Fox and Frank Josef) in the southern Alps. These are often part of an adventure trip to New Zealand,. You can do heli trips with glacier landings or other activities.
We rented our car from Hertz but there are lots of options. One-way rental, from Christchurch to Queenstown did not incur a drop fee.
Please feel free to ask questions!