The art of traveling with the whole family largely consists of A) Not going completely insane, and B) Not letting on to everyone that you have, in fact, gone completely insane.
Audiobooks can help.
You just have to pick the right one. Otherwise you might just as well sing about the Wheels on the **^%$#@ bus for seven hours – this still being better than the complete recorded works of Justin Bieber that your pre-teen daughter can and will inflict on you.
What’s it going to be? It can’t be too long – check the length, because you want it to cover most of the trip, but still reach a conclusion. It has to be something that every member of the family can – at the very least – tolerate. This includes mom and dad, who are as entitled to a vacation as anyone else. It has to be read well.
Goodreads is a review site by ordinary readers for ordinary readers. Here’s a discussion about audiobooks for car trips with kids:
http://www.goodreads.com/topic/show/140708-best-books-for-a-road-trip?auto_login_attempted=true
Here’s my own suggestion – a classic pirate adventure, not too long, with chances for your best pirate voices afterward – Treasure Island by Robert Louis Stevenson. At seven hours it’s fine for either one long trip or a there-and-back–again. It combines blood and thunder adventure for the kids (and dad) while being educational and classic literature – mom may like that part.