Thanks all - some awesome suggestions. I haven't checked out the Smithsonian website for a while (I get jealous looking at it!)

We are in NZ, our national museum focuses on geological history so it's amazing if you are into volcanoes and earthquakes etc. That is a weekend visit for us. Our own town museum is nice but quite limited. There are a couple of Dinosaurs and a bit on Maori but nothing in between.

I shall get busy looking up the recommendations!