I know that DH saw them back in September as part of the pre-parade and walking around one day, but then in December the pre-parade was all about Enchanted. In January I saw no pre-parade at all (and I was sitting in full view if any pre-parade goodness happened by).
This isn't characters, but if you like everything Ratatouille, check out the store-front window on Main Street. When you enter Main Street, go to your left, and check out the windows; it's pretty early on if memory serves. There's Linguini moving around in the scene as Remy teaches him to cook in his apartment, and it's really cute. While there, if you're a fan of Pixar and the little things they do, check out the whole window including the post-its on the fridge and wall, and especially the bottle of wine on top of the fridge.
It's not big characters, but it's a fun thing to look at!