[Glenda]

I am not certain whether you have already booked your flights, but if you are going via AirNZ, you can continue your luggage allowance on a domestic flight if it is part of your journey.

This is what they say:-

5.3 Checked Baggage Allowances
Passengers are allowed the following baggage. Any piece of baggage that weighs in
excess of 32kg will not be accepted for carriage.
(a) Domestic Services: 20kg maximum weight with a maximum combined dimension
(length and width and height) of 158cm.
(b) Travel to or from the USA, US Territories, Canada and Tahiti, or between New
Zealand and the UK via North America: All classes - 2 pieces of baggage per person with
a maximum combined dimension (length and width and height) of 158cm per piece.
Economy and Premium Economy - each piece cannot exceed 23kg in weight. Business
class - each piece cannot exceed 32kg in weight.
(c) All other international journeys: Each piece should not exceed a maximum combined
dimension (length and width and height) of 158cm. Economy and Premium Economy -
20kg maximum weight. Business Class - 30kg maximum weight.
(d) If part of the itinerary involves travel under the piece system, then the piece system
will apply to the whole journey. This includes Star Alliance Round-the-World fares.

The drive down to Wellington would certainly be awesome. I would recommend a couple of days in an Auckland hotel/motel to get over the jetlag. I would also recommend no more than three to four hour's driving a day as you will probably get the urge to doze off in the afternoons for a week or so! It is a personal choice as to whether you prefer to hire a rental car and stay at motels, or go for a campervan.

Alternatively, you could take the train.