For consulting it's my business clothing (very different from my previous job - programmer duds). I think of it as my superhero costume, and it changes how I think about myself, and how others do as well. Very cool.
Shirt and tie and somewhat dressy pants and District name badge. And it's true... I feel more professional as soon as I've got that tie and badge on. The badge says "I worked my way up and I know what I'm talking about."
I visit and help tech specialists at schools, and mostly they don't wear ties. So I want to dress better than the people I'm helping. It would not inspire confidence if I showed up to help them in a t-shirt and shorts.