Every year, we drive from W. Central IL, to Salem, West Virginia,and back, at least once, sometimes 2-3 times, we go evey year in the fall for Thanksgiving, and then some years in the summer for 4th of July or an August Family Reunion. We also usually make one or two trips to Nashville TN, which is 10 hours. We have done it with my daughter, from the time she was 6 months old, she's now 5 years old, and then the first time with my son, when he was 5 months, and he is now 3. The hardest time was when my daughter was 2 and a half and potty training and my son was 5 months and still nursing, there were lots of stops on that trip, and we made it a two day trip, staying overnight about 2/3 of the way there. Once they were each over 1 year old, we started making the trip in one day.
We always drive during the day, because neither of us is a good night driver - I fall asleep at the wheel, and he can't see well at night with headlight glare and bad depth perception. Also, when we go to WV, my hubby is going hunting the very next morning with his family, so he doesn't want to drive all night and be exhausted. We usually leave very early in the morning, like 5 am, and then we are there by supper time, or at least a little before bed time so thaty don't have to go straight to bed after being cooped up in car seats all day - they get some time to run and play. The kids do usually take about 2-3 one hour naps during the trip.
We always bring lots of finger food snacks and sippy cups with drinks and refills in a cooler. We always stop about every 3 hours for a break at a rest stop, park, or restaurant make sure many of these are places they can run around - even McDonalds playlands are a god-send on these trips - check McDonalds website to find which ones have playlands on your drive route!
Other tips are, we make sure to pack some toys they haven't played with for a while (you can hide them a few weeks beforehand,so when they see them in the car it is like new), lots of books, my daughter has recently liked books on tape or cd with a book to go with them and an old walkman or discman to listen to them with her headphones on ( check your local library) - you could do the same with MP3s on a player or phone, kids music CDs to play on the car stereo, we always take their magnadoodles, coloring books and crayons (washable - and in a ziploc, in case they are left int he car and melt in the summer). We buy some new cheapo toys at the 1 dollar store Dollar Tree or Deals - and wrap them and say every hour they get to open something new. We did have a DVD player that was portable for a while, but it broke, we may get another with the back of the headreast dual screens - we only used that as a last resort in that last couple hours when they are just so tired of being stuck in their car seats that they are crying. We also make sure we have their favorite toy/stuffed animal and their bed blanket that smells like home for security for them - also a kids neck pillow horseshoe shaped to keep their little heads form slumping over when they sleep - you can find these at WalMart and Target in the aisles with carseats and kid "gadgets".
When it was only my daughter and DH and I , whichever adult was not driving usually sat in back with her, to talk to and entertain her. Now, we play the games of finding the alphabet on signs, or finding certain things along the route - horses, cows, red car, blue car, barn, tractor....etc., talk about the traffic ( in a nice way), shapes we see in the clouds, teach about road signs, rules of the road, the way the car works, the things we see outside, etc.!
Good Luck! It is hard, but if you do it regularly, they become great little travellers, and that makes shorter trips a breeze!
Jessie