For only $2.99 each, these iPad eBooks allow your kids to either read Dr. Seuss's books themselves or have the books read to them (and they can control when the pages are turned). There is also an autoplay option, which may be good on those extra-long car rides.
If games are what your kids love, then the iPhone has got you covered: There are several types of Dr. Seuss cameras, a "Grinchmas!" kids' game and eBooks. With all this entertainment, you might not need to stop the car!
Think your kids can't handle the iPhone or iPad? Take a peek at this experiment done by FastCompany.com. It might just change your mind.