1

New Zealand cities cities are actually quieter in Jan as everyone goes to the beach! the most popular campsites and accom in popular resort areas are usually booked up at new year e.g. Bay of Islands but you should be able to find space the rest of the time if you book ahead. Remember New Zealand has a lot of space and a small population!
Make sure you get on the water in Auckland rangatoto is a great trip, visit the bay of islands, Coromandel, Rotorua, Tongorero crossing is one of the best day walks in the world. Weta studios, West coast of the south island Queenstown and the fiords. Then book your next holiday here cause a month isn't long enough!

2

You're right, it will be busier in January, but not so much that you won't have a good time wherever you're at. If you happen to be here on NYE, I'd say avoid Queenstown as it's hands down the busiest day of the year. Outside of that, I think you'll be sweet wherever you go.

3

If you set out to avoid the crowds what do you actually think you're going to see and experience? Not much I'd suggest.

4

The busiest time is between Christmas and New Year. Spots in camping grounds in any beachtown will be hard to come by. What are you interested in? If we know that, we can give you better suggestions.

5

Nelson/Abel Tasman is also pretty hectic around NY, but as others have said - if you avoid all the popular places what is left - spending your holiday in a deserted Wellington??

6

what all the others said... everyone goes to the beach in January.

There are some places that I'd probably avoid in the 1st week, like Whitianga, Whangamata, Pauanui, Paihia, Mt Maunganui... mainly because I'm not a huge fan of trying to relax in places where there are drunk teenagers roaming the streets. That tends to calm down a lot after early Jan though.

7

Thank you everyone for the advice. I don't dislike crowds. I was just trying to get a general idea of what it's like in most areas of New Zealand during that time of year.