Some other suggestions:
Melbourne, We took the local bus/tram from the cruise terminal. It was $15au. They give you an excellent map and at all the main transfers they're people who direct you. Very easy to use and goes to a lot of tourist areas.
Dunedin,We took the tour with Hal to Lanark Castle. Beautiful drive, beautiful gardens, interesting history.
Wellington, free shuttle with 2 stops. Go to the 2nd stop at Te Papa Museum, free, fabulous. The Botanical gardens, also free are a beautiful walk, but uphill. Long lines for the Cable car as tours jump the line.
Napier, take the shuttle to the Aquarium and walk back along the waterfront.
Tauranga, We took the Living Village Experience tour with Hal. Excellent, good meal, interesting drive saw Kiwi farms, tree farms, cattle and sheep.