Huxley: "A Brave New World" (fiction) & "The Doors of Perception" (non-fiction). Personally, I'm not a big fan of his (Huxley's) other work. A lot of it, including "Doors of Perception", borders on pretentious.
As for King, I think he's best book is "On Writing." His fiction is a little too repetitive for me; it's typically beautifully written, but there just isn't enough variation to keep me coming back. I've read maybe twelve King novels. They all had common factors:
1 A small middle-American town, most commonly in Maine.
2 A protagonist that is a professional writer.
3 An ensemble of quaint country-folk characters.
4 A creepy nursery rhyme, often repeated throughout the novel in italics; the juxtaposition of innocence and horror.
5 References to childhood trauma.
6 One dimensional villians; the bad guys are pretty much always pure evil.
7 Overly verbose descriptions.
8 Alcoholism, painted from an exterior perspective.
9 City-folk interacting with country-folk.
10 Supernatural elements/ entities/ abilities.
I liked Carrie (a novel about a girl with telekenetic powers), then I read Firestarter (about a girl who can burn things with her mind). I read the Shining (about a writer from the city who goes to the country to work on his novel), then I read Misery (about a writer from the city who goes to the country to work on his novel). I read The Tommyknockers (about a country town led astray by temptation), then I read Needful things (about a country town led astray by temptation). I read Cujo (about a killer dog), then Christine (about a killer car).
Carrie, The Shining, Needful Things, Misery & The Tommyknockers are great novels. His ability to write elevates the absurd and thematically repetitive subject matter of his work. It is all highly readable. It is engaging. But, I don't think he challenges himself enough as a writer. Because of the massive number of similarities between his work, a lot of the characters are interchangeable from novel to novel. He actually re-uses characters and character names from book to book. See: Randall Flagg, for example.
King is like a prolific romance novelist. He is, apparently, content to keep cashing cheques regardless of wheter or not he has something to say. His books appear to be written largely due to compulsion and/or the sheer momentum of his career. I like it when he has something to say. The Tommyknockers is probably my favorite of his novels, because - through his fiction - he delves into his own drug abuse. The book, as all good books should, poses questions. It gets the reader thinking. Therefore, there is compelling enough subtext to justify my reading five hundred pages.
He's such a fantastic writer. It's a shame that he limits himself to a finite selection of plot-driven supernatural suspense stories. "On Writing" proves that he is capable of so much more. If I ever read King again, I will finish The Dark Tower series. Though, his fantasy books fall into many of the same traps as his horror. Sprawling, overly verbose, descriptions. Monochromatic Good vs. Evil. Middle-American country environments. Every time I read King, I get a sense of deja-vu - and that's not a good thing.
Stephen King's books are too popular. He is like the McDonald's of popular literature. I know so many people who have read practically all of his novels, despite having read very little else. I used to fall into that category. Since broadening my horizons, I have little to no interest in picking up one of his books. From what I've heard, his more recent novels (post car accident) are all terrible.