I took a week at the end of October to tour the South Island of New Zealand. I realised pretty quickly that there is a lot to see, and shortened my trip to Christchurch -> Lake Tekapo (1 night) -> Queenstown (3 nights) -> Dunedin (2 nights) -> Christchurch (1night). Car hire is cheap, Jetstar offer the best deals and BBH backpackers are generally very good. Will have to go back!