7 days is perfect - you wont have enough time to see / experience everything, so will need to make more trips to kiwiland

Seriously, I'd concentrate on one of the islands only (north or south) and depending on in depth you want to go probably only 1 or 2 regions.

Lots of great wines. For anyone wanting to find out more on NZ, I'd suggest visiting the Australia, NZ & South pacific destination forum. There is a lot of information there - including a sticky. And quite a few locals willing to share info/advice.