I, too, first read the books when I was twelve. It took me more time to read them...but I always read things slower, to take stuff in more.
However, I've read the LotR several times since then, and the Silm. half way through (got stuck and died out on the Realms of Beleriand...I feel really dumb saying that here on the Downs), and I've also read the Lays of Beleriand. Those two books didn't really change my reading of the LotR too terribly much, it was just the more times I read the trilogy, the more I could get from it.
For instance, Sam's character, for one, I loved from the very first time I read it. The second time, I got to see more and more of that character. The third time I read it, my love for Sam spread to Frodo, who Sam loved so well, and I got to peek a bit into Frodo's character, and the farther I read on and the more I saw of Frodo, the more I loved him, too.
So, I guess you could say, that the way my reading has changed is, I've been able to delve more into the characters. Also, I've read the appendixes, and some history on Tolkien himself, and I will say that those things have shown me a lot more in the books. Like the story of Aragorn and Arwen...and then the bit of Tolkien's parents dying, and all that sort of stuff. It's very intriguing, really, what all he put into his books.
I like this thread. I don't know myself if there's been one like it before.
-- Folwren