We also have a slab foundation. We have beautiful riverbed rock in different shades along several outside walls. When it rains we don't have the problem of mud splashing up on the outside walls either. Check out a landscape supply place near you and see all the different varities of stone that's available. I've got a color called Western Sunset in my atrium and the orange and peach colors of this stone against our redwood house is really beautiful. It's easy to take care of, no maintenance at all.