Just finished rereading the trilogy - last reread was in 2002. Before that I hadn't read since college (maybe high school - not real sure). This time I read the 1992 "Centenary"edition illustrated by Alan Lee, since supposedly his illustrations for this edition served as the inspiration for a lot of the movies' images.
It's interesting how much of the movie's dialogue came directly from the book, although the characters saying the dialogue and the place in which it occurs changes in a lot of cases. One of the things that struck me this time was how much detail Tolkien put into place descriptions. He would wander on - frequently for a paragraph or two describing locations in such detail that it becomes very hard to believe that he wasn't describing a particular location he had seen. The same sort of detail is apparently in the appendices in volume , which I finally read, start to finish. The amount of detail he puts into the chronologies, the history of the kings of the various kingdoms, etc. puts the trilogy into such a historical context that you have to keep reminding yourself that this isn't real.
But the thing that just blew me away this time was the "translation" notes I had never read before, where Tolkien describe, apologetically almost, how he changed the real characters' names in translating the story from the original Elvish or Westron to try to get them to come across the same way in English as they would have in the characters' original tongues. I had read this in high school far enough to learn how to write using Tengwar characters, but I hadn't read the notes on translation of character and place names. It seems that Tolkien changed the character and place names to give them an English feel so they'd sound to modern readers like they did to the original. Thus "Merry" or Meriadoc was really Kalimac, and he chose the name he did because the shortened form "Kali" had the same jolly sort of double meaning in Westron that "Merry" has in English. He then casually mentions that Sam Gamgee and his father Ham were originally "Ban and Ran". All these changes were to "modernize and make familiar" the language and places of hobbits. Probably not surprising for a professor of languages, but this is incredible - it's like reading Shakespeare's notes on how he changed the facts of "Henry V" from the historical record. Except that there's no historical record here - Tolkien is making all this up, and then inventing backstory upon backstory upon backstory for it. This makes it more like George Lucas saying that Luke Skywalker was really Luca Skivversads, and Darth Vader was really Divvy Waba, but he thought changing their real names would make them work better for the movies. I can just picture what Tolkein must have been like after dinner puttering around his study mumbling to himself. I'll bet no one asked him what he was thinking more than once!
Of course the language of the trilogy is also hopelessly archaic, and you really come to admire (and thank) the scriptwriters for the movie for keeping the flavor but not the substance of the writing. Until this morning when I read the paper I had never heard of a living person using the word "alas" but these guys do it all the time. But it is still a phenomenal work - probably still the greatest work of imagination ever written down. I already have it penciled down to reread next year. I'm hoping to get the new leatherbound version to read this time.