My sleep button is waaay off to the side and inset, so it doesn't bother me much. I never use it, though. Don't see the point.
What I really hate about my keyboard is the "function lock". I don't think they make them quite like this anymore due to customer complaints, but when my computer starts up the F keys on my keyboard don't act like F keys. F1 is "help", F2 is "undo", F3 is "redo", etc. It annoys the heck out of me. I never use them for those "alternate" features.
Most often I end up playing a game or using a program that needs the F keys and I forget to hit the function lock before I start playing and I end up getting upset when I hit F5 to quicksave and nothing happens.
Edit: And apparently the function lock key doesn't even talk to the computer, so programs like AutoHotkey can't detect it or simulate pressing it. This thread made me go searching for a solution and apparently with my particular keyboard there really isn't one, due to the way the function lock key works.