Is Wellington worth adding to a New Zealand itinerary?
Wellington is worth it when it fits the route, especially for food, museums, harbour walks and the Cook Strait handoff. It is less convincing when added only because the ferry line needs a dot on the map.
Answer
Wellington has a sharper city personality than its size suggests: wind, hills, waterfront, cafés, museums and a compactness that makes it easy to enjoy without a car. It makes most sense when you are already travelling down the North Island or crossing to the South Island. It is weaker as a forced detour on a trip that mainly wants Rotorua, Queenstown and Fiordland. The mistake is treating Wellington as either essential or irrelevant. It is a worthwhile city when it supports the route; it becomes dead weight when it is added out of geographical guilt.