Good point. If you’re only used to US roads, add an hour or so to my driving times, to give yourself a safe margin. All the more reason to give yourself three days for the trip up from Wellington.
I’m just tossing out ideas here, but if you’re into the whole nature thing what you could do is drive up to Tongariro/Ruapehu from Wellington: take a day to do the Tongariro trail - some spectacular walking through “Mordor” - with a soak in the hot pools at Tokaanu as a reward at the end, stay overnight near the National park -the Chateau is nice if your budget’s not too tight - then head to Rotorua the next day, and Waitomo the day after that, ending at Auckland on the third day: fairly relaxed driving - and the driving is pretty - with lots to keep you busy on the way.
I kind of thought the glow worms were a bit meh. Nevertheless, the inner tube ride through the caves in the dark was unbelievably fantastic. If you don’t have a fear of the dark, it’s a must-do attraction.
Like others have said, the Tongariro track is spectacular. My bit of advice is that you really have to jam a bit to finish it in time to catch the bus back to town. I’m a bit of a SoCal dawdler (slow walker) and I definitely had to keep an eye on the time. But the trail is tear inducingly spectacular. I’ve never really seen anything like it.
Wellington is a really beautiful city. It reminds me of a homier uncitified naturey version of San Francisco. The Museum of New Zealand - Te Papa Tongarewa is a fantastic museum.