The Ghibli Museum is magic. It's made for kids, with child-sized secret passages and amazing things to see everywhere. And there's tons of kids, but of course the place is super popular with parents and animation fans. But, crucially, no cameras or photography are allowed anywhere in the museum. So unlike everywhere else in Japan, you don't have constant selfies and group photos happening -- just people enjoying where they are. It makes a huge difference.
It's also the only place in the world you can see a dozen or so exclusive Ghibli/Miyazaki shorts, including "Mei and the Kittenbus", the Totoro mini-sequel.