The energy savings may not be huge, but that’s not the only reason to take the stairs, whenever possible, instead of the elevator or escalator. There are health benefits too, of course, and the American Heart Association includes it as one of the simple things you can do in everyday life to be a little bit healthier.
I work on the 7th floor, and took the stairs up today, which I do about half of the time. I sit around all day already–might as well sneak in a little exercise when I can.