Tougher on the kids than the drivers.
I would also say that it will be tougher on the kids covering 500 miles a day then it will the drivers. One long day on the road, maybe 2, but 5-6 days, one after the other is a real test. You don't say how old they are but letting them have some time to let off steam is important. They have to be belted in when travelling and the back of an RV does not offer the most comfortable of seating over long periods. An RV is going to be slower and more expensive than a car and Motel room by the time you add up campground fees, fuel and rental costs, unless of course you own it and rental doesn't come into it.