One of my most delightful discoveries when I first started drinking real coffee as opposed to the stuff in a can was how easy it is to tell which region of the world a coffee comes from. Since I'm a smoker, I can't always pick out the subtler flavors, but the big notes literally sing out. It doesn't take much more than a taste or two to learn to distinguish a South American coffee from an African one or a Sumatran from a Caribbean bean. Do you have a preference for one region over another?
For me, it's Ethiopian, Yirg all the way. I love the earthiness of it, the subtle caramel silkiness and the rich mouthfeel that makes it feel like I've taken a bite of coffee rather than a sip. I also like my coffee with cream, and Yirgacheffe complements the cream rather than getting drowned out by it. But I'm not a one-trick pony. I find something to like in coffee from almost every region. Some of has to do with time of day -- I like the citrus *snap* of a good South American coffee in the morning, and the chocolate-and-fruit combination you'll find in a medium-roasted Caribbean coffee during the day. In the evening, though, I really love the earthy smokiness (and low acidity) of African and South Pacific coffees.
On the flip side, is there a coffee region that you just don't care for? I'm not a big fan of most Brazilian coffees, for example, which tend to be acidic to the point of astringency, and many of my friends routinely pass on the Yirgacheffe because it tastes "dirty" to them. Of course, that earthy soil quality is one of the things I like best about it. How about you? What do you look for in your coffee and does it vary with the season, time of day or other factor?