I mustn't give short shrift to this one: it's an utter delight, and "meta" or "postmodern" or something like that, in that it's a book about books, and a book that becomes the kind of book the characters want. What they want is magic, the kind of magic that takes ordinary people by surprise, and magic that requires them to learn its rules, tame it, thwart it, and pass it along when it's time to do so. And there are dragons, and a prologue to Oz, and an epilogue to an earlier Edward Eager book (Half Magic, also marvelous), and a song called "Chickadee Tidbits."
The problem I discovered in my nostalgia marathon? I read too fast. All of these books need to be about four times as long, so I don't lose them so quickly.