We set off for a road trip from Seattle, WA to Los Angeles, CA a couple months ago. We did two 9 hour legs to get from Seattle to Los Angeles. On the way back we did a 6 hour trip from Los Angeles to Monteray, and then we did a 14 hour trip from Monteray back home.
My kids are 4.5 (Allie) and 7 (Selena) and having mobile devices was extremely helpful throughout the trip. They provided such a variety of activities that we were never bored.
We had an iPad, an iTouch, an iPhone, an Android Note2, and a Win 7 phone and a Kindle e-reader for devices. Unfortunately we had no car chargers which was kind of a bummer.
We purchased Frozen, and one season of Wild Kratts from Amazon. Amazon's service is nice because if you buy video recordings you can download them for offline viewing and they support multiple platforms. Unfortunately and ironically they don't support Android devices unless it is their own Kindle Fire. This was a problem because I could fit a lot of content on my phone (the Note2) because of its micro SD card, and the battery lasts a long time, but my phone isn't supported so we were left with the Apple devices.
I could fit Frozen on the iPad, and I put all the Wild Kratts on the iTouch. The iPad's battery held up really well, the iTouch's battery only lasted a couple hours.
Books on "Tape" -
The Overdrive app via the library allows you to listen to lots of books. Floyd and I listened to Memoirs of an Imaginary Friend. Selena had Guardians of Gahoole on the Win 7 device.
Music is pretty obvious on any device. Allie and Selena liked listening to the Frozen sound track and Allie really likes the Fresh Beat Band.
We download Road Trip Bingo, and all three of us were able to play along on our own device. Unfortunately once we got out in the city many of the things were harder to find.
We had the app Toontastic on the iPad and we took turns making up a story and animating it via the app.
Driving through California after Redding is a long straight shot, which makes reading in the car much easier since their is not much risk for motion sickness.
Other non-device related entertainment-
I had a map printed out of Washington, Oregon, and California and I had drawn the cities that we would pass through on our way. Selena enjoyed tracing our route as we went along.
I had got the book Drawing With Children which has some step-by-step verbal drawing instruction. I would read the instructions to the kids while they drew in their sketchbooks.
The scenery of course was also entertaining. My favorite was when we passed Mt Shasta. On our way down it got dark and there was very little light pollution and the skies were clear so the stars were pretty impressive.
Overall the road part of the trip was a lot more pleasant than I had expected. When we did take breaks the kids and I would do sprints to stretch out our legs and get some blood flowing which helped deal with some of the fatigue of sitting for so long.