[selchie]

We've done two tours of a month each, and got a good overview and some detail of both islands. We were on holiday, visiting all kinds of out of the way places, and often staying for several days in one place. We were fairly relaxed and got to explore, though sometimes we were driving for the greater part of the day. No kids, so I can't say how they'll affect travel. If you're mostly visiting places you might want to live, 3 weeks might work. Auks & Hamilton aren't too far from each other - an hour or so? Welly could be a day or two's drive, depending on how "driven" you were to get there. You could get to Nelson from Welly well within a day. Chch would be perhaps a day or two's drive from Nelson - not sure, because we went the long way via the Wet Coast and Otago. You would have at least a few days in each city.

I can't think what to recommend visiting without knowing your interests. We do a lot of fauna & flora peeping and "treasure" hunting (usually in the form of beach combing). If for some crazy reason you wind up on the Coromandel, and cross between C-town and Whitianga, be sure to stop at the Waiau Waterworks. The kids will love it, and so might you. There are other fun places we visited, but they were mostly way out of the way.

Have fun!