* Rest stops are not for resting, they are for running around like mad. Resting is done when strapped into a seat with nowhere to go.
* Stopping to eat is futile. Kids who have been strapped in need to move. Feed them while they are strapped in. Eating kills time, and keeps tired parents awake while driving. Don't ask what my upholstery looks like.
* Strange amusements. I found these wax sticks in the dollar bin at my local craft store. They provided 2 full hours of entertainment on a recent plane ride. Better than the game system, far quieter, and lighter too.
* Leave early, stay late. If you can manage it, travel while the kids are supposed to be sleeping. They might sleep in the car/plane/train/boat.
* New toys. They don't have to be fancy or flashy, but something small and interesting, preferably in a difficult-to-open package will buy a lot of mileage.
* Don't forget the lovey. Whatever my kids love (we call them snuggle kitty and new bear), they travel with us. We're down to just one snuggle kitty because we lost one in the Honolulu airport, so they now travel exclusively inside suitcases, but when we get where we're going, the kitty and bear are there.
* Hotel pool (thanks to my friend Charlotte at Memories for Later for this one). The hotel pool will tire out a small child so much that they will sleep no matter how unusual their surroundings - and it might be their favorite part of the vacation anyway.
* Dishsoap-soaked paper towels. This one sounds odd, but before we leave, I drizzle a little dishsoap (we've already established that I like Dawn) on some paper towels and let them dry for a day, then fold them and put them in a Ziploc bag in my luggage. They go through security because they are not "wet", and it lets me do some dishes - like reusable water bottles and sippy cups at any hotel sink.