Sing alongs
A long drive or road trip is nothing without music, and even more of nothing without singing along to the music. If you don't want harmonies sung, and tunes bopped along to, don't even think of bringing me in your car.

Nips
If you are not aware of this lovely brand of candy, Nips are caramel type stuff on the outside, and chocolate on the inside. They are amazingly scrumptious, and last a super long time as opposed to other road trip candies such as gummy worms, that are consumed very quickly.

photographers
Someone in the car traveling must have the ability to take good photographs. How else are you supposed to remember everything and gloat about it later? Photography skills w/ a video taking skill component is a plus.

strong bladders
I'm sorry, but this is necessary. You need to be able to hold it, and hold it well. Stopping every hour is no fun, and ruins the flow (ew, wrong word there.) of the drive. Plus, I hate saying, "But you could've gone at the LAST gas station."

be a clean eater
Seriously, food all the over the car is icky, and because I don't drive, I'm in charge of keeping things tidy and putting people's trash away.