We have done this many times and most of the time it has been fine. But we had two nightmare trips. A couple of years ago, one of the kids got the stomach flu just as we were leaving. We decided to press on. Well, naturally it ended up with all the kids getting sick, and we'd drive for a bit, stop at a gas station so someone could barf, drive a little further, have another kid barf in the car, stop at another gas station to clean up the barf, drive a little further, stop for another kid to barf. And on and on. Kind of a nightmare drive, and they were still a bit queasy for the beginning of the trip (fortunately we had booked twelve days so there was time for everyone to recover!).
And then this past March we had another horrible drive, this time on the way home. The weather was bad (lots of freezing rain and sleet) so we could only make very slow progress, and when we stopped the kids couldn't play or run around outside because of the weather so they had a lot of pent-up energy. We ended up looking for Targets and Walmarts where they could run up and down the aisles. But they were very cranky and didn't want to be in the car.
So, just to say - if all goes well, it's really not too bad a drive. But add in a flu virus or a bad patch of weather and it can turn into a nightmare.
Teresa