All of Vonnegut, all of Hornblower, all of Steinbeck, all of Russo (especially Straight Man), all of Tuchman (Esp. March of Folly), all of, of course, Holmes and Wimsey, all of Cadfael, all of Tarzan and the Mars books (when I was younger), Quijote, most of Dickens, all of Will Cuppy, most of Twain (I especially love Fenimore Cooper's Literary Offenses, His Grandfather's Old Ram and the great Bluejay story, plus, of course, Tom and Huck), Catch 22, Maltese Falcon, Shogun and Taipan, most of Bruce Catton, Catcher in the Rye, Mockingbird, Stranger in a Strange Land, Lord of the Flies, Lucky Jim, Green Man, Wicker Man, Incident at Owl Creek Bridge and Horseman in the Sky, King Solomon's Mines and She, Robinson Crusoe, all of Richard Dawkins, Origin of Species, Wealth of Nations, Pinker's Language Instinct and Stuff of Thought, Candide, Sotweed Factor and Giles Goatboy, the Thunderhead trilogy; sheesh, typing one title brings several more. As soon as I post this, a couple dozen more will pop into my head.
There were a number of books mentioned by other posters of which I had never heard, but will certainly try to obtain. Not so easy down here; no libraries, but I will try, and thanks to everyone for the wealth of suggestions.