We drive staight from Richmond VA, and it takes about 12 hours, with reasonable stops. Maybe 13 hours if we hit traffic. If you are coming from Northern VA, maybe add 2-3 hours to that. We leave about 4:00 am., get there at 4:00 or 5:00.
We have done trips when we stopped overnight at a Hotel on the way, but have found driving straight through to be easier. You are excited to get there, so you keep going.
We never drive back home straight through. Always stay over in Santee, SC. We don't like to rush out of WDW too early in the a.m. on departure morning, and don't have the excitement to get us home that soon.