Sarah talked yesterday about a tendency to genericise, to reduce the details of our imagined worlds to the bare bones and let readers put their own filigree and flourishes into the story.
There is a certain amount of validity to this, since the world inside our heads is always much richer than anything on paper. But at the same time, if we strip down too far, we run the risk of talking heads in empty rooms (guilty, yeronner).
Heinlein was a master of putting in just enough to make the scene spring to life - and choosing the perfect detail to do it, usually something that implied a whole bunch more and built the world in our heads for us. Pratchett does the same in his fantasies, building on the more or less common heritage of fairytales to layer the details in a way that the more you know about history in general, mythology and the just plain weird, the richer his books become. As a quickie example, in Making Money, the parrot's squawk of "Twelve and a half percent!" has at least four layers of meaning that I've identified. There are probably more.
Who do you think gets it just right? If you feel like some examples where the author's gone too spare and left you with the talking heads, or too lush and given you way too much description instead of plot, feel free to mention those as well.