Plus the plot bounces around constantly, sometimes mid sentence, between characters and times and realities, that you get a better feel for the plot when you reread it anyway.
Books worth reading 10 times: Social Contract (Rousseau), Republic (of Plato), Apology (Socrates), As a Man Think, Inquiry into the Wealth of Nation (if you can muster the energy)
Books worth reading 3 times: Lucretius (on the nature of things)
And pretty much most books in the Great Books of the Western World list
Kerouac's "On the Road" is another that I read often. Somewhere in the once-a-year phase.
"Slaughterhouse Five" is another I read with some regularity, and I find it different every time I read it, as I have a new set of personal beliefs with which to apply to it approximately every time.
The great thing about it, IMO, is that the novel's not about the story from the movie, really, but nevertheless you can do to it what the protagonist is doing to the fictional Princess Bride book and tell it to your kids as if it were the movie, by skipping the "boring parts", i.e. the important parts if you're reading it as an adult. It's a great and funny adventure story for kids, wrapped in a melancholy meditation on relationships with children and recapturing lost time and experiences for adults[1], which is (rightly) absent from the movie. The story itself tells you how to adapt it for reading to kids. It's its own instruction manual.
I absolutely love the notion of a kid picking up the book as an adult, expecting the story their parents read to them, and being surprised by the discovery of the real story, hidden from them in exactly the same way the bits about economics and such were from the protagonist. It's simply brilliant, and a scenario I fully intend to set up for my kids :-)
[1] This is from memory—I read it several years ago, and if I revisit it I'm sure my take would have more nuance now, and would find this to be an embarrassing misreading or oversimplification.
If memory serves me, almost all of the memorable lines and jokes from the movie come word-for-word from the book. I'd assumed some of the jokes, e.g., those by Miracle Max (Billy Crystal) or Fezzik (Andre the Giant), were adapted to suit the actors. But they weren't. I don't know if that speaks to the quality of the writing or the casting or what.
I haven't read it recently (I have audio-booked it though), but I've probably read it ~25 times. (Often to refresh as new books come out, still often to just refresh).
It amazes me how, even in a book as simple, it still speaks to me.
One hundred years of solitude Blood Meridian