Some other good ones that have kind of the same flavor are The Phantom Tollbooth, by Norman Juster; any fairy tale book by Andrew Lang; The Happy Prince, by Oscar Wilde. Other good ones: The Island of the Blue Dolphins by Scott O'Dell, The Twenty-One Balloons by William Rene Du Bois; From the Mixed up Files of Mrs. Basil E. Frankenweiler.
Also, if you can find them in your library, John Gardner (who wrote Grendel, etc.) has some marvelous collections of original fairy tales.
C.S. Lewis also adored George MacDonald's childrens' stories and considered them an essential inspiration. : : : Anyone who read & loved The Chronicles of Narnia- : : Can you recommend other children's books?
: There are so many good children's books out there; I could go on for days. However, my personal best picks would be anything by E. Nesbit (she's a British author. She wrote some books about magic and some just about children), anything by J.R.R. Tolkein (he was a pal of Lewis'; they both belonged to a group called the Inklings), Alice in Wonderland and Through the Looking Glass, and the Wind in the Willows.