I agree with a handheld game. My step-DS and DD have to ride 20 hours round trip once a month to come see us and their Leapster and DS games have been so nice. I also print out worksheets from the computer and they like doing those. We bring movies from the library for them to watch.

I got a lot of activity books from the dollar store and I switch them out through the trip and those keep them busy for a while also.