Don't overlook the North Island - it has plenty to do, but Auckland isn't why people go to NZ. Bay of Islands, Coromandel, Wellington are all pretty cool.
South Island - Kaikoura has a year round resident whale that makes for great pictures. The drive from Kaikoura to Christchurch is very pretty. I would tell you to drive from Christchurch to Greymouth instead of the train to get good pictures. Mt Cook area, Queenstown, Milford....many choices. Kiwi Flyer is right. A bit more info can help us direct you.