I finally finished long arduous years of graduate school a couple of months ago, and have since engaged in a prolonged orgy of reading, reading stuff that I don't have to memorize, or cite, or otherwise expect to be responsible for knowing backwards and forwards.
So I'm reading lots and lots of genre fiction, and making up for several years of almost exclusively reading books that were related to work or school. A friend who's a mystery maven mentioned Robert B. Parker, and another friend is so very fond of Parkers' books featuring Spenser that he named his dog Spenser. So I tried one of Parker's Spenser novels.
I really really liked it. So I tried another, and then a third, and now, I'm engaged in hunting the books down and reading 'em all, in order. There are 36 Spenser novels (Parker has written a number of other books, including at least one young adult novel). I say "in order" because there's an over-arching narrative thread about Spenser's life that progresses through the novels, even though each of them very much is written to be read as a stand alone.
What makes the books for me is not just the characterization, and the story—which tend to be interestingly complex and very believable—but the language. Spenser has a true voice; I grew up in New England; I know Boston, I know how guys from Boston sound, and Spenser is one of those guys, right down to his love of the Sox. Then Spenser is a wise-ass; he's got the body and build, and the broken nose, of a tough guy, but he's a lot smarter than many other characters think when they first meet him. This is a tough guy private eye given to introspection; not mere navel gazing, but questioning his own, and our, basic assumptions. Spenser's a well-read but very middle class ordinary guy, but the love of his life, Susan Sherman, is a smart shrink, with definite feminist leanings. They've had a long term relationship, and while very clearly devoted to each other, they've had problems. His best friend is a not-really-on-the-side-of-the-law tough street-smart black guy. So there's a lot of reason for Spenser to constantly examine his assumptions—and in so doing, we the reader examine ours. He's done pretty amazing things in terms of being realistic about the fact that Hawk is a black guy, without turning him into either of the two most common black guy stereotypes within the genre (black guy as hoodlum, or black guy as Noble Savage). Parker's done similar things with other characters— he's one of a handful of mainstream genre writers who writes about gay and lesbian characters as matter of factly as he writes about tenured faculty, or Norwegians.
And in addition to all that, they're just plain fun books to read. I've been pleasantly surprised by plot twists, and very much enjoyed the way Parker is more about character and story than straight forward plot. Parker is not your average mystery writer though. He served in Korea, and attended Colby College in Maine, has a Ph.D. in English literature from Boston University, where his dissertation was on Chandler and Hammett.
If you're curious, I encourage you to check out the official Web site, Parker's blog (yes, it's really him, not a PR hack), or the very fun Yahoo group devoted to Parker's books, especially the Spenser novels. And last but not least, here's a very interesting interview.

