I'm bang in the middle of a reread now; I've lost count of how many there've been. I'm 55 now, having first read it in my early teens, and it's astonishing how it just keeps growing and changing with you. Even after all these years, I'm still surprised by a painterly description of a cloud, or the sense of comfortable rootedness of a little Shire lane, or a little "aha, I never noticed that correlation before, that's what those orcs were doing", or "hmm, that's an odd word to put in that sentence, I wonder why he picked it?" followed by a fascinating bit of research.

I've recently started the Letters too, and can thoroughly recommend it. It's fascinating and oddly cosy to get a direct tap into a mind you know so well at second hand, through its fiction.