Bay of Islands, north of Auckland, is very pretty and (from a local point of view) very historic. Napier has a lot of handsome art deco buildings - it was rebuilt after a severe earthquake in the 1930s. Rotorua and the thermal areas are fascinating, though full of tourists; and the scenery around the volcanic plateau in the middle of the island is striking. Mt Taranaki (Egmont on some maps) looks like Mt Fuji, a near-perfect cone, but often covered in cloud. And I'm a great fan of Wellington itself, less so of Auckland, though Auckland has better weather. For wine, west Auckland, Hawkes Bay and Martinborough (outside Wellington) are good.