My little daughter is an avid and discriminating reader. We go through children’s books like nobody’s business. The most engaging books for her by far have been the Eric Carle one’s. 1,2,3 To the Zoo and The Very Hungry Caterpillar are her absolute favorites.
I too love them for their collage work and beautiful colors. On his website Mr. Carle has a few neat slideshows showing his technique, which includes painting on tissue paper and then cutting them into the shapes of small critters for his books.
And, if you are ever near Amherst, MA, he has a museum too.