My favorite haunt in the bookstore is the "Sci-Fi/Fantasy" section. I'm a lifelong TV/film sci-fi fan, but in terms of books I go more for fantasy. I don't know, sci-fi literature often just doesn't do it for me; there's a little too much pretentiousness in science ficiton, because it's so easily used to reflect modern political and social criticism. Also, though I love science, science fiction often gets bogged down in technobabble, and if it's many times boring when TV and films do it, it's even worse in book form.
This is not to say, however, that I don't enjoy a good sci-fi book. In fact, I just read, and am now recommending, John Scalzi's Old Man's War. Excellent book! The title pretty much says it all: it's the story of a future society in which old men and women are recruited into the Colonial Defense Forces upon retirement. They're given new bodies, trained to fight, and serve to protect human colonies and fight other species for new ones on the relatively scarce number planets with suitable conditions. It's just a really interesting meditation on growing older, loss, and personal growth. And, though it is technically "military sci-fi," it doesn't bog itself down in the armament minutiae and ooo-rah that that particular subgenre is so prone to. It's just a very fast-paced, very interesting, very gripping story. It took me only a few hours to read (though I do, admittedly, read fast).
And speaking of both Scalzi and sci-fi literature's appeal (or lack thereof), here's a very interesting discussion of modern science fiction and its image problems that's been sitting in my bookmarks since December. Fascinating read, both for the post itself and the comments.