My girlfriend spent 3 weeks in NZ on a business trip in late February and she didn't want to come back home. Since it was a business trip, they didn't have a lot of daylight time to really cut loose but she did get to enjoy a couple weekends there. She was blown away with just the outdoor environment there. They visited the family of a coworker and she said the back yard was full of ripe avocado trees, macadamia nut trees, olive trees, citrus, etc. And just tons and tons of exotic plants. Of course, they were there in summer so I'm not sure how active that stuff will be when you guys go.
She also really enjoyed the markets there, both food and material goods. But of all of the things she enjoyed the most, it was the food. I'm not sure of the location, but I know that for dinner one night, they ate at a rotating restaurant up on this tower/needle. She took photos of her meals (she's funny like that) and some of the plates were amazing looking.
Oh, they also had a great time snorkeling in Auckland (I think it was there) but I'm not sure the water will be warm enough in October. One of her coworkers had to be taken to the ER after being slammed into some rocks and dislocating his shoulder.
I'm jealous of you guys. Have a great time and take lots of photos! Sounds like an amazing trip.