In reply to iantoday:
New Zealand is a big ol' country with lots of slow roads, so try and narrow down a bit where you will be, or you'll spend you're whole time driving.
From my limited experience, the best climbing on North Island is the Froggat are, where it's also fairly easy to find people to climb with.
If you have a week, I'd head to the south island and go to Paynes Ford. I thought it was amongst the best rock in NZ, but more importantly easy to fins people to climb with (Hangdog campsite), and lots of other stuff to do (great multi day walks, sea kayaking etc).
If you just wnat bouldering, Castle Hill is the obvious choice, but persoanlly I didnt like the climbing there.