I don't know anymore how many times I have seen these movies and read the books and it always gets me, impossible to watch with a straight face and every time it feels that the story becomes more important to me. I can't explain how mind blowing these were when we watched them in the theaters for the first time back in early 2000, I knew how they were going to end since I had read the books but I think I chewed half of the chair in front of me :D once in a lifetime experience.
Also I highly recommend reading the books, there are characters we don't meet and events happening differently or in different order. Good example is that there is a whole chapter missing when the hobbits return to Shire, it is amazing in the books but in movie format it would have not worked. I think the movies are as a good as they ever could be, masterpiece through and through but there is so much more of it in the books.
Can't wait for the Hobbit movies.