I feel sorry for anyone who would take the amazing opportunity of driving a luxury car across this amazing country only to squander it by white-knuckling it non-stop along the highway all day with only a gas station toilet break. Take a side road, explore the back country, stop at a bistro, stay overnight at a b&b. Otherwise, why not just catch a flight?
On a return trip, usually one way I'd do that, but the other way is Interstate / Freeways, get there quick as you can. Time is often a factor - you only have so much time off. Plus, driving with kids, you don't want it to take longer than it needs to.