You can't go wrong with a sport coat. My office isn't very tie suited, now and then when clients visit our executive staff may wy wear a suit, but normally just a coat. I think coats go a long way, and you can feel more relaxed in them, rather than a full suit/tie. +1. In summer we often go real casual around here, but I am always wearing a sport coat to work. I think it is practical compromise between casual and suit. Depending on what kind of unexpected action comes up, you may look a bit "too formal" or a bit "to casual", but you normally don't stand out too much. I feel comfortable that way. I mean, if you are wearing only a polo and suddenly there is a "tie meeting", well, you may feel quite awkward. With a sport coat and dress shirt, even without tie at least you look more or less dressed. On the other hand, even if most of the office staff is running around in polos and short-sleeve shirts, wearing a sport coat does not look too odd. Yes, I find it quite practical. Most of the day it is just hanging on a hook on the door while I am working with my shirt sleeves rolled up, but still, it is nice to know that it is there.