We did Virginia to California in three days for a job. Longest day was 1200 miles. One of us was driving the station wagon with the kids, dog and cat while the other drove the biggest UHaul moving truck they had. I'm not sure which had the better end of that stick. I DO NOT recommend this! We were a lot younger and not so smart. Not to mention we had younger, less cranky joints. Got to CA with $600 left and no place to stay.
Now, we try to limit it to 300 - 350 miles. We went 600 in one day and it was too much for us. If time isn't a factor, which seems to be the case, take a lot of side trips and eat like the locals. You'll have more fun on the road less traveled.
