A sisal rug is so versatile.  It has become a staple in interior design over the years and I don't believe it will go away anytime soon.  It is perfect for any design style and the texture adds so much to a room.  Of course you can layer more sophisticated rugs over it too.

For a softer feel underfoot, consider a low loop-pile wool rug that has a similar look. Then pop an underpad underneath for the ultimate in comfort.

They are sold at different price ranges, so consider one for your empty floors for a nice winter touch.