I did a search on Hilary Knight's illustrations and noticed that he had a lot of beautiful illustrations in full color. He illustrated Cinderella, as well. I love those illustrations! What I like about his illustrations are his use of line (sort of wispy looking), facial expressions, staging of the body or body positions, and the composition of the pages. I have a lot to learn from him.
There is a page in Eloise where it is drawn in the perspective of looking down on a fancy room above a chandelier. I don't know if I could ever draw anything like that. It's discouraging, yet inspiring at the same time.