Fortress more than I should, less than I'd like. Adventure mode far far less than I ought to, for balance. And, in light of the latest message I'll have to admit that Forum Watching (and more) is my biggest time-waster expender, but that's because I can generally do this while at my post here at work also doing the other things that I need to do.
(I know some people say that they can get away with DF displaying n front of their colleagues, quite easily, but my own are definitely tech-savvy enough to know I'm not manually defragging/similar, and on top of that DF-savvy enough to try to annoy me[1] with "killed any more dwarves lately?" as a general comment, although they'll sat that regardless of whatever is on my screen.)
But, really, I ought to increase my Adventure Mode play, to balance things. I feel guilty that I'm not taking advantage of all the newly developed architectural stuff. (But as yet I've still not gotten a full handle on the minecart stuff for Fortress Mode, either.)
But what with everything else I want to spend time on (and need to spend time on) what I really need to do now is increase the number of hours in a day to 48... no, make that 72. I'll put that on the To Do list.
[1] My fault for actively asserting that I try to keep them alive, once. They're people who expect you to be as abrasive a personality as they are. I don't actually fit in with that philosophy, but at least I know enough to bear their little foibles.