I use the livingroom floor as a "design floor". It has carpeting, so a bit easier on the knees. However, when I sandwich, I use the tile floor in the greatroom because it is a large space and I can tape the backing to the tile to ensure it is smooth. Depending on the size of the quilt, I sometimes need to continue to lay it on the tile and re-smooth between quilting sessions. I use the kitchen island for smaller quilts. I am approaching 50 and so far have had not had problems with knees and getting up and down from the floor, but I imagine those days will come soon enough!