I found a quiet space in the hotel where there was a marble floor. I normally do taiji on a smooth wooden floor, so this was a change. I also usually do it in bare feet but now I’m in sneakers.
Every such change, no matter how small, matters. You’re always working in a medium, not a vacuum. The air around you (water if you do the work in a pool), the clothes you wear (or don’t), the floor beneath your feet, has an effect on what you do. This is as true in the mental worlds as in the physical ones. You cannot think thoughts your language doesn’t have the words for. That’s why learning to draw, and learning another language are so important. These activities give you other “languages” in which to think.
Anyway — surface. Marble is an interesting surface to work off. It’s got no give to it, hard and unyielding, but having low friction. It’s easy to spin on it, more difficult to plant weight for the kicks and fast turns. It has a lot of slip to it, too: my form ranged much wider across the floor than I expected.