Whew! I just finished working my way through Minders of Make-Believe: Idealists, Entrepreneurs, and the Shaping of American Children's Literature, by the great Leonard Marcus.
He spotlights the earliest giants in the children's book world--the first children's librarians, book reviewers, publishers, authors, illustrators, and editors--and traces the development of the industry over a couple hundred years.
It's full of lots of fun behind-the-scenes peeks (when one condescending bigwig called Jean Karl a "juvenile editor," she called him a "senile editor" back and said, "good children's books are never juvenile."). And it has tons of interesting backstories (including how the knowledge of Sendak's at-that-point prickly relationship with his editor Ursula Nordstrom informs Marcus' reading of Where The Wild Things Are.)
But the best part is how Marcus places children's book publishing in context with both economic and cultural changes. I kept thinking, "Oh, so that's why..." It's definitely a work of serious criticism, but I recommend it highly!
However, if you're looking for fun anecdotes you can work into your RA interviews, check out Anita Silvey's 100 Best Books For Children; if you want shorter, highly readable reflections on children's literature and culture written by a gifted essayist, try Alison Lurie's Don't Tell the Grown-Ups and Boys and Girls Forever.