The Hobbit by J.R.R. Tolkein

Such a classic, there's very little I can add that's useful. That said, I am putting down here what I often forget and wish to remember: First, The Hobbit is a gentler, funnier book - less intense - than Lord of the Rings. As such, it is suitable for a much younger audience (ostensible reading levels notwithstanding). Reading aloud, I've had much success with this book from early elementary on (really - as young as about six or so). The plot is nicely divided out into story-shaped chunks, which makes it just right for bedtime fare - each chapter is largely its own episode, as it were. And - well, it's interesting enough for the whole family. Not something every book, even those good enough to read aloud, can boast.