S.G.
Hi C.,
We've taken several trips involving drives of 6-7 hours with our kids (6 boys: 15,13,11,10,3 & 4mos - but before the last was born). I know this isn't anywhere near what you'll be doing, but here's what worked for us... We bought a car dvd player - you can get them fairly cheap, and I think they're worth the $! We also brought along activity books - the kids' favorite was Mad Libs, which we all did together. The only danger of this is additional bathroom breaks because we were all laughing so hard we had to pee! Good music and plenty of kid-friendly snacks and drinks were also essential.
I remember long road trips when I was a kid (from IN to Boston usually), and we did a lot of reading and talking and playing games like finding different state license plates and car bingo. My parents were also really good at finding places to stop along the way that my brother and I found interesting - that really helped break it up. If you can find a hotel with a pool, even better - gives the kids something to look forward to at the end of the day.
I hope this helped a little...Good luck!
S.