I highly recommend renting a car / vehicle even if you have more time than I did. I believe it is the most flexible way to see a place as wide open as the South Island. Here is a quick summary of my tour...
Heading from near Palmerston North to the capital, the Tararua Forest Park offers many weekend tramping opportunities, though the wild winds that strike this part of the country are a constant threat. The open tops provide vistas stretching from the Wairarapa to the Kapiti Coast and south to Wellington Harbour.
The Abel Tasman Coastal Track is a breathtaking, casual walk around a spectacular, unspoilt coastline. This is a haven for anyone out there who loves the sea. There are brilliant, blue lagoons, estuaries and tropical island sanctuaries. The beaches, oh those beaches are simply a delight covered with sand that is so soft on your skin it feels like powder.
When you say Rotorua, people roll their eyes and nod dreamily. Rotorua is a mystical and magical place where steam rises from the ground, geysers erupt, mud pool bubble and hot springs steam. Rotorua is primarily renowned for its hydrothermal activity which has drawn tourists since the 1800s.