I think you should have an honorary "partially animated" section just so you can include The Wall.
But as long as Watership Down is in here I'm happy.
This was a TV Movie, but it's probably the best adaptation we'll ever see:
Wind in the Willows (Cosgrove Hall) http://www.imdb.com/title/tt0086590/
If anybody lists Avatar, it has to share it's placement with Fern Gully, LOL.
EDIT: Oh fuck, just remembered a few more possibles...
1954 version of Animal Farm
http://www.imdb.com/title/tt0047834/
The Devil and Daniel Mouse
http://www.imdb.com/title/tt0262368/
(Another Nelvana production - ie: Rock n' Rule)