Another vote for LOTR and The Hobbit (read several times over the years )although I've only read them out loud once, years ago, to my two girls as books at bedtime.

Took several months.

Actually I probably did read them out loud twice as each night we would discuss the previous evenings chapter and find that one or the other had dropped off before the end so we had to re-cap from the last remembered part of the story.

Great books and the girls still remember those months fondly. They buy me the Tolkien calendar each year.