I have 5 dogs that use a small fence area I call the dog yard. I use cedar mulch, it keeps the smell down for quite a while and the dogs don't bring in any mud whatsoever and no dead or yellow grass spots. I usually rake off the top in the spring and all a new layer and every other year scrape it all away and put down a good deep layer. I have two flower beds to off set the mass of mulch and a couple of trees, vertical planters etc. to dress it up because you see it from our living/dining room windows and french doors. I love it, it can be work because any mulch decomposes but I like it. I would be concerned with the rubber mulch, I think it would get really hot in direct sun and may hurt dog pads and may smell like rubber tires in the heat and humidity. I have thought about some of the latest generation astro turf because it is softer and looks more natural than it use to, but it's only been thoughts. My husband may think I am nuttier than usual, so I have kept the thought to myself!