I'd forgotten about Up. That was a great movie. Peak Pixar (between Shrek and Up, has to be their golden age).
I can't really respond properly to this thread, because I've mostly forgotten all the kids movies I ever saw. And the ones I remember being emotionally moving (like when Bambi's mom died) I don't know if I would still feel the same way if I saw them now as an adult. And I won't see them now, because I don't have kids.
"Brave Little Toaster" freaked me out as a kid. Watched parts of it as an adult and found it even sadder
This one's more nostalgia-feels. The design of heaven, especially, with the clouds, pastels, the carpet with the design, the streamers, the watches, etc. is things...yes, things...I don't have a word...It's like a sad Kirby level...