Hondo and Fabian by Peter McCarty, as well as the sequel: Fabian Escapes and an earlier work, Little Bunny on the Move. All of these have one thing in common--their very soft, nostalgic-like artwork.
Anita Lobel's Nini Here and There, a story of Nini, a cat who lives in the city going with the family on vacation in the country. Another beautiful book of artwork, some pages you might even consider framing (if you can bear to remove a page or perhaps find a used copy that can be taken apart.)
The Horse that takes the milk around is simply a wonderful example of a time long past--when horses were harnessed to carts which were loaded with milk bottles. The Milkman and his horse then "took the milk around." A true classic and collectible item, this book was published in 1946.
Anything by Janell Cannon, but my personal favorites are Stellaluna and Verdi.
True Kelley's series of art books and artists. The way she tells the story of famous artists is through a class project presented by an ordinary student who learns so much. One example is Smart about Pablo Picasso: Breaking all the Rules. In fact, check out all the Smart about books, even though not all are by True Kelley.
Olivia books by Ian Falconer are simply full of joy and mischief. Olivia is the classic case of a gifted child.
Another artist--the master of imagination and invention--is David Wiesner. His three Caldecott books will simply amaze you: The Three Pigs, Tuesday, and Flotsam.
Zoe Sophia, a schoolgirl noted for her brains but not her looks. An author and an illustrator paired to create these two books, Claudia Maunier and Elisa Smalley. I wish they had created more. One takes place in Venice, the other in New York. Both provide details about Zoe Sophia's deep attachment to her interesting great-aunt, travel, and mystery. All in each book!
That's my list of wonderful children's books for now. Enjoy!