I keep mine on vinyl/lino tiles, they are birlliant, I got a granite effect so it looks nicer on the eye, and it's so easy to clean, by far the best thing I've used, also theres no impaction risk so its the best of both.
1. No impaction risk for your pets, 2. Looks nice for you
If you live near a B&Q they do packs of five/six tiles in all different effects and colours ranging from £2.98 to about £8.