M.S.
First of all, I love the Xanax comment! LOL!!! It's true, you need a sense of humor!!
We have done road trips with our kids at all ages. When my oldest three were babies/toddlers, we drove through the night..there was really no other way to do a 14 hour trip with kids that young. However, we did stop those when both my hubby and I reported hallucinating while driving! We now have a 14 month old to add to the mix and we are considering it again, but we are much older now, and our bodies don't bounce back like they used to. However, it's pretty stress-free if your kids are good sleepers. Anyway, on to the day driving.............
A TV. We would never have gotten anywhere without one. We rent as many dvd's as we can and also bring all the older ones that they haven't seen for awhile. My 9 yr. old has a Nintendo DS, or a leapfrog if you have one. My kids also love to draw, so lots of paper, pencils, etc. I would suggest a zipper bag for the crayons, markers because the cardboard package they come in or even an artbox can tip over and spill pretty easily. Pack a bag for each kid because they may not be sitting next ot each other the whole time. You may want to pick up some new inexpensive items - you can even wrap them, which is something I'd do when we flew, also. Head to a consignment shop, hit up garage sales, etc. where you can get books, small toys for dirt cheap.
We have a cooler that plugs into the lighter to keep cheese, fruit, etc in. It beats having to open a traditional cooler all the time. If you do go with a standard cooler, I would recommend the frozen ice blocks (they are plastic and you can find them at any Walmart, Target in the cooler aisle). This way, you aren't dealing with melting ice that you can spill or have to dump. Also, when you get to your destination, you can refreeze them for the trip back home. If you bring drinks, I'd forego the juice boxes that are pouches. Once squeeze and it's juice down the crack of the seats. Also, make sure you have plenty of napkins, wet wipes and plastic sacks for garbage.
Now this is going to sound disgusting......but we always make sure we have empty water bottles. Our two oldest are boys and it doesn't matter if we make them ALL use the restroom before we leave a reststop, etc. inevitably, one will have to pee within 50 miles. If we didn't utilize the pee bottles, we'd be stopping at least 5 times as much as we planned. If you are uncomfortable with them taking off their seatbelt to do the deed while driving (understandably), you can make a quick stop at any exit ramp. No need to even get to a gas station. There would be no way for us to have made it to a gas station many times!! Plus, so many times we'd get off the interstate to find a place for the kids to go and we'd end up driving 5 miles into some little town trying to find a place with public restrooms. Very frusterating! For my daughter, we had a blow-up potty we got from www.onestepahead.com (I think). We would set it up between the middle row of seats and she'd pee in that. We tied up the bag and disposed of it at the next stop. A friend of ours took two of the kids back to our home state one time (a 10+hr. trip). He had always thought we were crazy for our "bottle tip" UNTIL he drove with them. He called complaining how many times they needed to stop!! LOL!!
Anytime you do stop, any physical exercise is good. Jumping jacks, races, etc. to get the blood flowing is fun. If you know approximately where you'll stop, check out which hotels have pools - a great way to burn off pent up energy!
As far as the squabbling goes, good luck :) If it's getting out of control, have them sit apart and do different things. Or bring in the whole family on a "I Spy" game. You know, I spy with my little eye....something green. Make sure you bring their pillows/blankets so that they can curl up and nap if they are tired-especially if you'll be doing any of your driving at times they'd normally be sleeping. If you are staying in a hotel, make sure you have one larger bag, possibly, with the whole family's overnight items and change for the next day. It's kind of a pain to have to drag each member's whole suitcase into the hotel room-especailly if it's late at night and you and your hubby are trying to carry in sleeping kiddos, too. It's much easier to bring in maybe one or two bags that have essentials for the nighttime and the next day's clothing (kind of like a carryon for an airplane). You don't need much for one evening/morning when you're in a hotel.
Last of all, relax and go with the flow. It's sometimes hard when the kids are stick-a-fork-in-me-done with traveling. Just a couple quick, attention-getters can get you a few...more....miles, like opening the windows, kicking off your shoes, singing a song loud with clapping (like If You're Happy and You Know It), or dancing in your seat. Sometimes that's all you need isa few minutes of happiness to get you to the next stop. Good luck and have fun!!!