The plastic resting mats are GREAT. They let the urine and poop fall right through. The wood, on the other hand, lets the urine soak in to it, and poop stay on the top and get stepped on, and the rabbit's fur can end up matted from exposure to the wet and dirty conditions.
If the wood is just a loose board you intend to throw away after a week or two, then OK. But remember how disgusting it is, and how YOU wouldn't want to stand on it barefoot, before you leave it in any longer than that.