I know this will alienate me forever from die-hard Tolkien fans, but I felt The Lord of the Rings (the novel, that is) went on too long after the Ring's destruction. Specifically, the scouring of the Shire didn't work for me. I see how it's important to show that the war extended even to the gentle faraway Shire, but our good professor basically already showed that with what happened to the four hobbits (actually five; Bilbo too). In terms of pacing, it felt like a big stumble or hiccup. We were winding down and watching what happened to each hero as he or she went home, then boom, we're back into battle scenes? Didn't like it. As far as I'm concerned, it's okay if Saruman does meet his doom back on his ruined tower, from a tidy arrow fired by Legolas.
For that matter, I also felt the Tom Bombadil sequence was a big hiccup or stumble on the path of getting the action started. Therefore I totally understand why Peter Jackson didn't put either of them in the film. And I utterly forgive it. Though I know my elf- and dwarf- and hobbit-costumed friends will raise an outcry at my saying so.
(Admit it, you miss the days when 90% of my LJ posts were about LOTR. It's kind of nostalgic, my posting this, isn't it?)