What do I wear if I want to look professional, be comfortable and still feel cool

One among many possible answers to the most popular question from last week's open thread

Are we human, or are we cucumber?

The question that garnered the most upvotes at last week’s open thread was how to look cool at work. Cool but professional. The majority of the queries suggested the environments you work in are professional, but not super strict, so I was like, oh, what about a suit? Originally, actually, I was like, This prompt is on …