This is what I do....I've driven alone and with hubby with 2 children and more as young as 18 months and will do it with an infant later this year and as a toddler next year.
We cannot drive overnight. Both me and my DH cannot stay awake and it becomes too dangerous for us to attempt. So our routine for long distance travel....
We leave between 2am and 5am depending on our plans and when we wish to arrive. Sleeping kids are placed into the van and we do not do any movies so that all kids go back to sleep. We drive until the sun is coming uo. If kiddos
are awake, DVD player goes on and sometime between 7 and 8 am we always stop at a cracker barrell. Kids are changed out of their jammies and get at least an hour out of the car. This closely resembles our home routine--wake up and eat.
Then for the rest of the trip...it is movies and only stops for the potty for parents and trained children. But no more lenghty stops.
We find this works for us.
We are blessed with zombie children who can be entertained for hours. Last February, we played the signing time videos quite a bit because my speech impaired some could not speak. We used the captive time to educate him (almost 2yo at the time). He started signing a week or two later. We were traveling for a funeral--so I did not have time to fully plan that trip. I had ordered the videos independent of the trip, but they arrived just before we left.
Toddlers are great for traveling. They still (usually) sleep quite a bit.
Our next trip is in 3 weeks and I'm cheating.

We are driving 90 minutes to the auto train amd taking that to it's end point and then it is a 90 minute drive to the new house. Baby will only be 2.5 months old and I will be driving by myself. Too long of a trip with a nursing infant. So auto train it is.