I've been to Mitaka and seen the Ghibli museum. It was by far one of the absolutely best things I did while in Japan. When I went they were screening a different short that was sort of like the Little Prince, with this environmental message where this kid grew tiny planets from seeds. I can't remember the details because this was about 7 years ago. Still, I remember enjoying everything there a whole lot. I only wish I had a child so they could play on the Nekobasu and throw stuffed makurokurosuke at the other kids.