Count me in on those who want a copy of the list made from this thread!
Rick, you won't remember me, but I spent a Sea Music Festival (Mystic) weekend following you around like a puppy and have fond recollections of standing in the parking lot of Roaring Brook (Canton CT) talking (or listening) far longer than it took you to load up. I wish you the very best in your treatment. (It tickled me by the way to see one of my shots from Canton at Mudcat!)
So many great suggestions here; I certainly would second anything by personal favorites Robert A. Heinlein (get past the juveniles and the Stranger in a Strange Land, because the Methuselah series, culminating in Time Enough for Love, are my favorites), Tony Hillerman, and Ellis Peters. Remember Ellis Peters is Elizabeth Pargeter and her history-based stories of Wales and her nonfiction are definitely worth finding.   
I have not seen anyone mention some other favorites:
Madeleine L'Engle's books are definitely not for children, and do hunt up the others beyond the Wrinkle in Time series.
Saki (H.H.Munro) wrote perfectly brilliant short stories and some short novels, incredible wit with at times a bitter social-critic edge, but fall-down laughing quite often.
P. G. Wodehouse was possibly the most underrated master of English literature, probably because he wrote light comedy, but his mastery of the written word is incredible. Besides Jeeves and Wooster, look for all the Blandings Castle series, the Mr. Mulliner series, and the Psmith series. He thought his New York stories the best, but I would take his English countryside ones any time. His short stories fill volumes (often available in one big composite) and his novels are wonderfully carefree (and often available four or five to a volume).
And you MUST (and I never shout) hunt up Dorothy Dunnett. She is a Scot writer and my nominee for best author of English-language fiction. There is a series of contemporary (well, 60s-70s) mysteries, the Dolly series, featuring a portrait painter/James Bond type who lives on his yacht (the Dolly) and involves a series of extremely smart and quirky young females in mysteries with plots and characters you would never suspect; if I told you the first I read involved a dyslexic Scottish make-up artist telling her story you would scarcely have a hint of her imagination. They are currently out of print but I see them regularly in used paperbacks and on Amazon and have been published with different titles; one series (U.S. I think) are all "Dolly and the [something] Bird" but check the intro or you may get duplicates. She also wrote the six-volume Crawford of Lymond series, which was a cult item on a number of campuses years ago, but are all in print again and excellent; this series has chess-related titles (Game of Kings, Queen's Play, Disorderly Knights, Ringed Castle, Pawn in Frankincense, Checkmate). Her most recent series of eight volumes is the House of Niccolo series, massive and complex and fascinating; incredible reads. Both of these series are history-based and it is a revelation to check the character lists in the frontispieces and see how many of the characters are historic. Niccolo concerns the rise of international trade and intrigue, centered from the 14th century Brussels outward from Iceland to Asia Minor and North Africa, and Lymond starts in Scotland in the minority of Elizabeth I but ranges through most of Europe and Russia. And brace yourself, my nominee for Best English-Language Novel Ever Written would have to be King Hereafter, in 11th century Alba (now Scotland) and Norway; she starts with the same set of legends and scraps of history that Shakespeare used for MacBeth, but what a tapestry she weaves.
Good reading. Be well.