Mine has a bare concrete floor that I covered my working area with those rubber tiles that lock together. Got them from Harbor Freight for $9 a 4 tile package. Keeps the feet warm, easy to keep clean, HOWEVER, one word of caution when walking on them. Make sure there is no water under them! My basement leaks when it rains hard from a certain direction, poor seal between the old foundation and the new wall they put in for the addition where my shop is. I didn't notice that some water got under the tiles, the water leading to it dried. I took a nasty spill when the tile went one way, and I went the other. My shoulder it still bothering me from that.

I have since put down some textured floor paint so now the tile has something to grip to and wont slide.