I've been using a product called aspen crumbles from sun seed. It looks nice, is easy to clean and allows burrowing. It is an aspen product obviously but rather than shavings of wood it is made from the bark of the tree The only drawback is that mold can grow under water dishes if they overflow. I've solved this problem by either using elevated water bowls that have the added benefit of providing a hide underneath or making sure I place the water dish directly on the glass.