After dark, try to avoid Queen Street harbour-side of FORT STREET, its dark and all over kind of creepy. Also wise to stay out of Myers Park as it can be considered a shady place to be.
A lot of locals will warn about being on K (Karangahape - pron. Ka-ranga-happy) Road at night - don't listen! Its a buzzing street that you can walk safely - just dont sneer at the drag queens or prositutes and you'll be fine!