AKICILJ: floormats for standing desks?

(I posted this on Google+, but I figure I should post it here as well....)

I'm thinking about rearranging my office to make more use of the standing desk that I have.

Any suggestions for an ideal floormat to use to stand on for this? Best would be something that is reasonably cat-proof, and I expect to be using it barefoot rather than in shoes.

Also, it would be nice if it doesn't break if I put a stool on it, since I sometimes use a stool to sit at my standing desk, but of course I could just move the floormat out of the way first.