Taupo is a much nicer place to stay than it is to drive through when you're on a hurry to get somewhere else. If you're going to spend half a day relaxing by the lakeside, much better to do it in a deckchair with a book than in the driver's seat of a Corolla calculating what time after midnight you're likely to be hitting Auckland.
It's beautiful, that cold, deep lake - the city sits right on the edge of it, looking across toward the mountains in the distance. The skifields are just over an hour away by car, making Taupo an ideal place to sleep before a long day on the slopes, and to return to later for the greatest tasting pint you'll ever have. Watch out though, it'll go straight to your head (on a related topic, that giant trout statue is harder to climb than it looks).
Staying in Taupo gives you all the benefits of a city - shopping, restaurants, things to do - but if you'd prefer somewhere more quiet, there are some beautiful little towns in the area. Like Mangakino, on the shores of Lake Maraetai, where the only sound you'll hear is the splash of the paddleboat. Just don't complain at 9pm when you feel like going out for a dance - no, the paddleboat will not "take you into town".
If snowboarding isn't your thing - maybe you enjoy your wrists in their current configuration - the Tongariro Crossing is a spectacular day out. Voted one of the best day walks in the world, you'll see views you'll remember for the rest of your life. But you should probably take pictures anyway, just in case.
Aside from that, the Taupo region offers jetboating, bungy jumping, kayaking and quadbiking. In fact, take a natural wonder, add a form of transport, then put '-ing' on the end and we can pretty much guarantee that somebody will be offering it. Sky diving? Check. White water rafting? Check. Mudpool surfing? We'll see what we can do.