Doyle's good. Have you read his Challenger stuff?

select Hardy Boys?

Three Investigators (earlier episodes - while slightly precious I suppose they're not utterly so, and they are hardly cozy - they even get creepy every now and then. Get the ones featuring 'Alfred Hitchcock')

The EARLIER Cat Who... series (see: Cat Who Saw Red)

Tony Hillerman is a truly marvellous writer--his books feature clever, well crafted stories, well developed characters who actually grow and change book to book, and absolutely beautiful descriptive writing--plus you gain a lot of interesting insight into the culture and beliefs of the Navajo, Hopi, Zuni and other tribes of the Southwest--all without the faintest shred of coziness. People of Darkness, Skinwalkers, and The Wailing Wind are three of my favorites.

If you want a more traditional police-based mystery, I'd go with any of K.C. Constantine's Mario Balzic series. What really stands out immediately here is the realism of the cases--there are no cheap theatrics or iprobable twists, just the bleak detail of the actual sort of cases a homicide detective might face. Here too, the setting does a lot; Balzic is the Chief of Police in a small, economically depressed town of Italian-American families outside Philadelphia, and figuring out whodunit is often a matter of piecing together who owes what to who. Plus, he's a great character--he drinks too much, but this is not milked for melodrama, he's in bed with the (reasonably benign) local mob in an effort to keep the peace, and often the best he can manage is a partial solution. Try "A Fix Like This" to start off with.

Some of my favorite non-Christie authors:

Colin Cotterill - Laotian Coroner in the 70's - but low on pseudo-forensics because the newly installed communist government gives him no budget. Small doses of magical realism related to Laotian folklore, but the cases and solutions are all matter of fact and real.

Barbara Cleverly - (Joe Sandilands series) Scotland Yard detective traipsing around India in the twilight of the colonial period. Modern sensibilities about race and gender.

John Dickson Carr - (Also writes as Carter Dickson) Master of the locked room type of puzzle. Really marvelous solutions you should have known all along. Mostly set in England in various time periods.

Jospehine Tey - Scottish author, well-written, post WWI, usually in cities, tricky conundrums.

Chuck Todd - Post WWI, Scotland Yard detective is too shell shocked to be around people in the city, so they send him out to obscure cases in small pockets of england that may or may not have begun to transition into the 20th century. This series has a psychological subplot related to the shell-shock, but it is not overwhelming.

Arthur Upfield (Napoleon Bonaparte series) "Bony" is a half-aborigine detective who wanders australia between the World Wars, solving only the most intractable cases in only the most interesting rural settings.

There is nothing to feel guilty about in reading books by any of these authors - they are novelists whose novels involve clever murder mysteries.

I gave my wife the first of the Cleverly series, "The Last Kashmiri Rose." She told me last night she wishes her book club would read it, because the characters and settings are more interesting than those in the last two book club books.