*Liquid consumption is to be kept at an all time low. If they say they are thirsty. Tell them they are not. If they insist they are thirsty, and begin to cry, continue to tell them they are not, until their whining starts to disturb and/or influence their siblings**. Then, and only then, place 2-3 ounces of water in their Snackeez. Or, in George's case, hand him the tail end of your water.
**Which reminds me. If any of your children even so much as starts to mention the words: bathroom, pee, potty. etc. STOP them!! Immediately. Having to evacuate your bladder is highly infectious. In fact, if you hear the words, "I have to" just yell "NO!!!" (Or SHHH. Or Don't you dare say it. Or Hold it. Or I swear to god if you say that out loud we are leaving you at the next stop. Ok, maybe not that harsh. But you can consider it, up to you.) Don't even let them finish. Even if it's not restroom related, they don't "have to" do anything. You're on a road trip. They're stuck in a car. Rest my case. Just no.
PS. I chose to list first a food related item because if you've ever thought to yourself "if they say I'm hungry one more time, I'm taking them all to the fire station" when spending a full day at home. You will think this again. Within an hour on the road.
All the electronic devices. We have 2 Leapsters, an iPad, and a Kindle. I made sure those suckers were fully charged, new batteries, etc. I considered loading a few new games, but didn't get around to it...would have helped, maybe, but not vital. If they are bored enough, anything is fun. Note: if this isn't an obvious Road-trip-with-children life hack for you, then I advise you NOT TAKE A ROAD TRIP.
All the activity books. Big ones work, but easier to carry around, store (and throw away) are some of the smaller packs you can find these days. Some even come with the stickers and crayons all packaged in tidy little zip lock bag. They don't stay like this. The crayons get everywhere, as do the stickers, and the trash. Why can't they just keep the booklet in one piece? Is it is really necessary to tear out each page? Bite a few corners off? Spit it at your brother? WHY!? Warning: Crayons melt at extreme heat. Well, maybe not even extreme. Warning: Crayons melt at mildly elevated temperatures. Do with that information what you may. Note: If, for their entire lives, you have not insistently and firmly repeated "Stickers are only for paper or clothing". Even when they simply catch site of the things. Then I'd reconsider supplying the 3rd row of a minivan with them. Unless, of course, you enjoy using a razor blade to scrape stickers off windows. Or find the random splattering of Teenage Mutant Ninja Turtles about your car appealing. Then by all means, sticker 'em up.
PS: We also have some of those magnadoodles and an Etch-A-Sketch. Also great options.
Afternoon departure. Leave after lunch, if at all possible. Kids are inherently most active in the morning. They tend to do a lot of their business (you know, like #2) in the morning. They are hungry. Thirsty. Antsy. Both days that we attempted to leave before 9am, we stopped nearly every hour for various reasons. It's infuriating. A good run at the park, swim at the pool, walk around the block, is extremely helpful to gear them up for a long drive. All three of our 5 hour stints happened between 1pm-6pm. Most of the kids, even the non-nappers, dozed off for a brief period of time in that post lunch daze. Note: It is important to have a driver equipped to stave off their own mid-afternoon rut. Lucky for us, I don't get tired.