When it comes to buttons on a suit, less is more in my opinion - in fact, my bespoke suits and the ones that I design are mostly one-button. When wearing the more popular three-button style, however, it is important to know how to button it.
The general guideline is "sometimes, always, never". Meaning, sometimes fasten the top button, always fasten the middle button, and never fasten the bottom button.
My personal rule, however, is "never, always, never". Only fasten the middle button. And keep it fastened at all times, unless sitting down. Like Tom Ford (the best menswear designer in the world, in my opinion), I agree that men look better with their jackets closed (more streamlined, more "put together", more tailored, etc).
As an interesting side-note, Mr. Ford has been known to go around buttoning mens jackets at parties, as if he were doing them a favor. After all, most modern high-end suits have a rollover lapel, which basically hides the top button from being seen, and makes it awkward to button. Therefore, just leave that top one alone.
Yours in style, Style Blogger