I would recommend just about anything by Marcia Muller (Sharyn McCone is the most consistently good series of all time), Michael Slade (if you can stand blood and horror), Raymond Chandler, Ross McDonald, T. Jefferson Parker (with the exception of California Girl. The MWA membership mush have been smoking meth, crack, opium, and reefer to give it an Edgar.) Dashiell Hammett, P.D. James, Dick Francis, Cynthia Harrod-Eagles, Mary Anna Evans, and Kate Wilhelm (Barbara Holloway is a pretty good series character, too, and Wilhelm is an excellent writer).
Agatha Christie can be hit-and-miss, but The Murder of Roger Ackroyd, Death on the Nile, and The ABC Murders are all classics. The three Miss Marple novels I’ve read are pretty good.
From Ellery Queen’s work, I would say *The Green Coffin Mystery *(more radical than Roger Ackroyd), *The Egyptian Cross Mystery, Four of Hearts, Calamity Town, Cat of Many Tails *(the first, and still one of the best, novels to deal with a serial killer), The Player on the Other Side, And on the Eighth Day, and Face to Face. Can you tell I’m an EQ fan?
*Trent’s Last Case *by E.C. Benson
The Hound of the Baskervilles, The Adventures of Sherlock Holmes, and The Return of Sherlock Holmes by Sir Arthur Conan Doyle
In her novels spanning *The Man with a Load of Mischief *through The Old Silent, Martha Grimes is usually pretty good, but after *The Old Silent *, which is one of the best mysteries ever, IMO, they pretty much suck with the exception of The Lamorna Wink.
Sue Grafton’s Kinsey Milhone series is uneven, but some of the novels, especialy I & K are excellent.
Ed McBain’s 87th Precinct series is pretty good, but the later ones with Fat Ollie got on my nerves.
For a mixture of mystery and sci-fi, Asimov’s *The Caves of Steel *and *the Naked Sun *are hard to beat. I would also contend that the second two Foundation novels from the original trilogy are also mysteries in their own fashion. (I’m not giving anything away by telling you that they involve the search for Trantor.)
*The Moonstone *by Wilkie Collins. T.S. Eliot called it the longest and the best of the detective novels.
*The King of Methlehem *by Mark Lindquist