The Frontier Culture Museum and some other kid-friendly stuff in Satunton may be up their alley. Wrights Dairy Rite has good ol fashioned greasy burgers and milkshakes. The Massanutten indoor Wave Park is only about 45 min away and good for a full day of exhausting little ones. Depending on the weather, the leaves may be beautiful at some places up that way. They could also ride the ski lift to the top for the view and hike down.
That can only keep kids entertained so long though.