I've read the entire Sherlock Holmes corpus about 3 times, I think. I find that after about a 10-year interval, I can't remember how most of the stories end, so it's like reading them for the first time.

I read Tom Sawyer and Huckleberry Finn several times as a kid. It was a long time before I realized that the editions I had then were dumbed-down abridgements for kids. I reread Huckleberry Finn recently, an unabridged edition, and was surprised how much was new to me. I enjoyed it immensely.

Likewise, I read Great Expectations long ago (or thought I had) because it was a school assignment. I reread it recently and had the same experience. So much was new to me that I figure that must have been an abridgement, too.

I'm pretty sure I read 1984 more than once. I probably should read it again. In fact, it probably would be a good idea to reread a lot of the books I enjoyed as a kid.

Tom Sawyer, though, was a disappointment when I tried rereading it as an adult. I don't think I ever finished it.