Midwestern Family Cruisers: Anyone choose to drive?

We are driving to Galveston from Manitoba this year for our cruise. Our kids are great travelers...we are very lucky. One of my husband's strategies is to leave the first morning around 3am in an attempt to a good distance under our belt while the kids are still sleeping. We try to drive as far as we can that first day in an attempt to make for shorter days to follow.

We are near Denver and are doing a family cruise in October out of Galveston. My wife and I have done several cruises from the Galveston area and have always flown into Houston then shuttled to Galveston, however with the kids in tow this time (10,9,5) the cost for five of us to fly to Houston and shuttle to Galveston is too much. By driving we will save almost $650. The distance is a bit over 1000 miles, so its very doable and we will take a leisurely two days to get there, a day early. We drive quite a bit with the kids, so we will have all the entertainment packed and ready and also have the portable potty ready to go. When we are driving long distances, I always try to stop at places where the kids can get out and literally run around for a bit. It helps them get the ants out of their pants and it seems make the drive a little more relaxing.