I love rereading books. You can get something new out of an old favorite every time. Speaking of our recently departed Galactic Hitchhiker, I have reread all of his books several times. I have read Catcher in the Rye more than twice, and I have a different reaction to it every time. Also the Lord of the Rings series - I was really too young to appreciate it the first time I tried it. I think it is almost necessary to read Umberto Eco several times before you really comprehend his depth (and that's only in translation!)