Don't think I'll ever bother rereading it, though--the whole thing is focused on problem-solving over how the people doing the problem-solving are being affected by everything. Which isn't a bad thing, please don't get me wrong: it's very well-written and enjoyable, and I'm glad that I read it. But there's not much outside of that going on. It's a book about a guy who got stranded on Mars and how he gets off Mars again, and once you know what happens, that's pretty much all there is.
Confession time: the real reason I bothered picking up The Martian is because I recently read Close to Home, which is an excellent AU (still a WIP, but we seem to be well past the cliff-hanger stage, and the author's fairly regular in updating) where the main character winds up having to spend a lot longer in complete isolation on Mars. There's still a strong element of the survival aspect to it, but the focus is much more on the psychological repercussions of being completely abandoned on a hostile and empty alien planet. I've read it twice so far--once just on a whim, because it was bookmarked by an author I liked, and then just after finishing The Martian, and it holds up both on its own and in response to the original novel. And I can definitely see myself revisiting it again in the future, because of the shift in focus.
See, Close to Home is about a guy who got stranded on Mars and how he gets off Mars again, but it's also about what happens to someone when they are absolutely cut off from the rest of humanity, aside from the digital bits and pieces left behind on his teammates' laptops. It's about what it's like to survive the unsurvivable--and then have to deal with everyone else's reactions to that. What would it be like to go from having no companionship aside from the recordings of medical lectures, to suddenly being stuck with six other people 24/7 in a small spaceship headed back to Earth--where everyone's spent four years thinking you're dead? Heck, what does it mean to survive, if you're so altered by it that you can't even recognize the person you used to be?
That's the kind of thing that's much more rewarding to revisit, because these are questions that touch on some more fundamental ones about what it is to be human. Every time I revisit them they're going to apply to me in some different way; alternately, the steps for successfully getting off Mars remain the same no matter what's going on with me personally.
But I don't want to make it sound like there's no value in the original novel. After all, the people with whom we spend time affect us, whether they're flesh-and-blood or exist only on paper. It's good to read about people who are faced with really hard tasks and refuse to be daunted by them. Sometimes those tasks are physical, sometimes they're mental--sometimes they're emotional. So read The Martian. And then read Close to Home--or vice versa. They'll both help you be a better person.