I used to work in a corporate office where there was no defined dress code. It seemed that the closer you were to the CEO, the better you were expected to dress. I sat about 30 feet from the CEO's office, so I always tried to dress just a bit more professionally that the norm.
Then I realized that my job sucked.
At that point, I started to push the boundaries of denim at work. Denim blazer? Why not. Denim skirt? The girl around the corner is wearing jeans and a sweatshirt, for crying out loud. I always made sure I looked put together and professional, but I had fun pushing the envelope while I was at it. "Sticking it to the man", as it were.
And if you can stick it to the man while wearing a beret, then ain't life just grand?