Driving at night was the best. Lots of stops, and as had been suggested, bring some brand new toys for the kids.
One thing that I dont think has been mentioned is that driving at night allows you to get through the cities much faster. I always pay attention to what time my proposed schedule gets me to cites known for congestion. In my sierra vista- San Antonio trip hitting Las Cruses/ El Paso at the wrong time could easily lengthen the trip by an hour. This is a big deal on a long drive with kids. We cant plan for everything, but doing good planning makes the trip much more likely to go well.
Another point is that everything that you forget to bring takes time to get. It might not seem like a big deal, but making an unscheduled and normally unneeded stop into Safeway will cost at least 15 minutes (getting to the parking lot, walking, picking, waiting in line, walking back to the car, dealing with the kids, getting back on the highway) even if you are as fast as you can be in the store. . Every time you need to pull off the highway you are losing time. Sometimes you have no choice, but 15-30 minute chunks of time add up fast, and unscheduled stops to get something that you forgot are not relaxing like a 1 hour long breakfast is.