My therapist has a bunch of chairs in his office. Well. Three not counting his. Two are your typical like chairs you find in a waiting room (wooden, cushioned seats, wooden armrests) and they have a table in between. Then he keeps another fancy office chair.

I kind of do whatever I want. I've sat on his floor. In the waiting room type chairs. Recently I've taken to grabbing the office chair and rolling across his office like a kid before propping my feet up on the table. Which is cool because he props his feet up on his desk.