Thanks to everyone for all the great help! We are going to camp out in Coromandel for a couple of days and try to get rid of the jet lag. Then fly down to wellington and then the South island for the driving and scenic sites. Wish we had months so we could see it all!

The North and South Island trains/visits have different pros/cons.

North Is - variety of scenery, better temps, beaches, volcanic regions etc but there is only the one main train service. I'd take a bus mostly or a train to National Park from Auckland. From there you could do the Tongariro Crossing/head to Taupo and Rotorua etc.

South Is - fewer people, more scenery and sheep(!!), but better train journeys there - the TranzAlpine and Coastal Pacific trains are the main (only I think...)services.

Found this nzbyrail site the cheapest for tickets... but maybe try others too? http://www.nzbyrail.com/

These two trains run between Christchurch and Greymouth daily on a return trip basis(TranzAlpine) and also Coastal Pacific from Christchurch to Picton on a return basis.

Both great experiences plus have new carriages now on offer.
They take about 4hrs30mins for the TranzAlpine to just over 5hrs for the Coastal Pacific.

I did both trains - found the TranzAlpine is a relaxing journey and nice to see such lush scenery. Coastal train is great also - liked the beach scenery but you feel less away from it all.

Take your jacket and take some snaps when you go out on the outdoor viewing deck of either train - its a great 'wake you up' experience!

You will enjoy NZ for sure so you should take a look around!

I highly recommend the Auckland-Wellington train jorney on the 'Northern Explorer', and the ferry crossing Wellington to Picton and onward 'Coastal Pacific' train to Christchurch.

These make a great way to travel in comfort from Auckland-Wellington-Christchurch, not only for the scenery but for the history.

Be aware that the official Kiwi Rail Scenic Journeys website suppresses the cheaper fares if you browse with non-NZ IP address, so to get around this and buy the cheaper fares online, see the advice on www.seat61.com/NewZealand.htm under 'How to buy tickets'

We flew into Aukland, drove to Hamilton (our daughter was a student there) and used Hamilton as a base to tour Rotoura and surrounding areas, well worth seeing! Then took the train to Wellington and the ferry to Picton and train to Christchurch (pre earthquake). Took the train from there over Aurthur Pass and then drove to Te Anu and Milford sound. Then down through Queenstown and around the bottom of the island to Duneden. Then flew back to Aukland and toured the northern part of the North Island by car. All forms of travel were easy, driving in New Zealand is not difficult, think America in the 50s, and many things are more accessible than by train. I would consider mix and match. Have fun, I envy you. It a spectacular country! Of everywhere we have been, and we travel a lot, it is the place I would most like to live. It's just far away from the US.