Other I’m sure will respond re weather possibilities. In our four cruises from Melbourne to nz we have missed Dunedin once re weather, others have been fine.
I personally would def want to do Dunedin train (talkie? Gorge), tauranga has the Rotarua thermal springs and lunch on island queen. The local Māori come non board and do the hukka and get volunteers to be taught. It was seriously a highlight being so close up to the performance.
napier is fine to walk around and has a really good shopping area (car free) where we have bought some excellent things. (Nz wool sweaters etc.
wellington has a good shuttle from princess, drops at various points in town. Get off almost opp the tram/train thing up mt Wellington (last time there it was $3.50 ea) then get off at the top, have good look round then you can walk down through the botanical gardens. A great day costing. $3.50 each lol,
enjoy 🥰🥰