I am a Kiwi and lived in NZ for all but the last 20 years when we moved to Australia. I go back to NZ every year. Due to go back in February next year-all my family still live over there. February is summertime and the weather is usually quite settled and warm. It depends what you want to see-if you love snow/mountains etc then winter is also a special time. The scenery is so varied and you do not have to travel far to see quick changes in the scenery. I have lived in both the North and South islands and think the South Island is the prettiest but both have their own special things.
If you want to know anything in particular let me know.
KIWIAUSSIE JEN