I recently mentioned the Miami Museum of Science and Planetarium, in Florida. Apart from the planetarium, I remember loving the museum in general. I loved it especially because it had a lot of hands-on exhibits.
This will not be a revelation to anyone: Kids love to play with things. And when I was a kid, the Miami Museum of Science had many places where you could push buttons, turn cranks, shift levers, and so on. Things moved, things make sounds... and the whole place came alive for me, or so it felt, from the large dinosaur skeleton in the entrance lobby to the back corners of the museum.
In contrast, the National Musum of Natural History, in Washington, DC, for example, is full of exhibits to look at, but not to play with. Art museums may be aimed more at adults, but science and natural history museums are for kids, and they're best when they're playgrounds for learning. Instead of showing diagrams or static models of volcanos, set them up so the kids can take apart the layers, so they can press buttons and have them “erupt” loudly, so they can pretend to be the explorers from Jules Verne's Journey to the Center of the Earth (and that can prompt them to read the story when they get home).
I'm sure the Miami museum has changed a lot in the last 35 years, and I don't know to what extent it's still a hands-on place. But from the web site it looks like there's still quite a bit of that there. I think the next time I'm down that way, I'll check it out.