Slate tile is a natural product with a quality image. Surprisingly, slate isn't expensive - tile starts at about $2 per square foot. It's durable and low maintenance. The texture of slate tile also makes it a good non-slip surface for bathroom and kitchen floors. I'm using it in the kitchen.
I selected Daltile Vermont slate in 12-inch-squares. It's relatively smooth, with no deep clefts. The thickness is nice and consistent too. It cost me $3.80 per square foot on sale.
While I have slate tile on the floor of the kitchen, my small house has a cork floor in the living room and bedroom. It is softer and warmer for those areas.