I have carpeting in my sewing room, I don't think it's a great choice, pins get "lost" in the carpeting..... threads are hard to vacuum.... my chair has to be on a plastic mat otherwise the wheels don't move freely.
If I had a cement floor, I would consider getting some of the wonderful cushioned rubber mats that are made for cashiers and others who stand alot in their jobs. (they're not cheap but you can get them in all different sizes) It really does help to "cushion" the strain on your back if you plan on doing much machine quilting.