We take a couple 1300 mile trips a year. We invested in personal DVD players. We don't watch much TV/video the rest of the year, so this is a huge treat for my kids. We generally only buy videos right before one of these trips. My dh is "drive it straight through" kind of guy and I can't read in the car for fear of nausea. The movies allow the trip to be a kind of treat for my kids and not a chore for dh and I. We generally only stop for potty breaks, sleeping, and the occasional "extra" snack.
We store the DVD playerss in the big suitcase we only use for our mega-travel. When traveling around town, or on less than 5 hour trips, we listen to audiobooks. We love the Little House books, the Focus on the Family radio theater dramas, Adventures in Odyssey, anything read by Jim Weiss the Story Teller, Hank the Cowdog books read by the author, the Story of the World volumes on CD by Susan Wise Bauer and lots of other things we check out from our library.
Three of my children can draw in the car (one gets sick) so I bring sketch books, pencils and crayons. Pipe cleaners in lots of colors make excellent building/entertainment material for the car.