I loved Akaroa just south of Christchurch. Went just at the end of peak season so it was still all open but not busy. Good to note that a a lot of the little towns like that are pretty seasonal so I wouldn't go at the depths of winter (dead and closed) or height of summer (feral with tourists).
For cities I love Wellington. The waterfront is π
The young Seagoons have been in NZ for about a year now and they love Akoroa tho with them it seems it's all just a base to visit LOTR sites. Last week they were in Edoras.
Queenstown / Wanaka which I visited a couple months ago - just spectacular, so naturally beautiful. I went mainly for skiing but it would just be as good in summer I reckon. Can do all the hikes and trails without worrying about snow and the views would be even better with clearer weather. Otago wineries, heaps of adventure type activities, you can make a great family holiday. The one downfall is that this area is pretty expensive because itβs very touristy, itβs like holidaying in AU prices.
Just driving around is beautiful, much spectacular scenery, especially the mountains. We donβt really have anything like it in Aus. Visiting the Franz Joseph glacier was a highlight. You can see it by booking a guided walk. The ice formations and blue ice colour is very interesting and beautiful. I saw it about 15 years so I donβt know how it is now, because warming and glacier retreating etc, but if itβs still available to see it I would highly recommend it. (Who knows how long it will be there for?)
Edit: just looked it up, wow it has got expensive. You need to do a helicopter flight to get to it, but still Iβd say if you can afford it in your holiday budget itβs a very unique experience.