[Mithalwen]

Well a glance at the posting figures for CBC might give a few clues, but I think it is reasonable, if not stating the obvious, to say that the most significant chapters for the plot are likely to be found at the beginnings/ends of the books (and by that I mean the 6 books not the three volumes). This is because they "set up" situations that the rest of the book will follow or to be "cliffhangers" to keep the reader in suspense til that thread is resumed.

But since LOTR is more than a story, it is a major - arguably the most reliable - source of information on Middle Earth and so depending on your interest in that world different chapters are important - for me those containing elves and elvish rank quite highly and those involving Tom Bomabadil are virtually disposable! - but again the CbC proves that that opinion is far from unanimous.