Fourteen days lets you do one of the islands properly with time for slow stops, or both islands as a highlight reel with one Cook Strait ferry crossing in the middle. The single-island option (usually South) covers more national parks, more drive variety, and fewer rushed days. The both-island option covers the headline destinations — Bay of Islands, Rotorua, Tongariro, Wellington ferry, Kaikoura, Queenstown — but every day is a moving day. Decide which trip-shape you want before choosing pickup/drop-off cities.
Option 1 — South Island 14-day loop from Christchurch
Christchurch → Kaikoura (2 nights) → Nelson and Abel Tasman (2 nights) → West Coast glaciers (2 nights) → Wanaka (2 nights) → Queenstown and Milford day-trip (3 nights) → Tekapo and Aoraki (2 nights) → Christchurch. About 2,200 km total, no ferry. This is the route most repeat NZ visitors recommend for first-timers because every day has a clear destination.
Option 2 — Auckland to Queenstown, both islands
Auckland → Bay of Islands (2 nights) → Rotorua (2 nights) → Tongariro (1 night) → Wellington (1 night, ferry next morning) → Kaikoura (1 night) → West Coast (2 nights) → Wanaka (2 nights) → Queenstown (3 nights). About 2,600 km plus the 3.5-hour Cook Strait ferry. One-way drop fees apply on this route — they're standard and worth it for the time saved versus driving back.
What 14 days rules out
You won't do Stewart Island, the Catlins, the East Cape, or the Far North in 14 days alongside the main loop. If any of those are non-negotiable, stretch the trip to 18-21 nights or pick one less of the main destinations.