D.B.
CDs that you all sing along to. Great family activity. You can get classic tunes, not just the really annoying ones!
Get into looking out the window to find sights: bridges, barns, the color red, cows, motorcycles, trailers, a blue sign, etc. We used to play travel bingo with the kids or just get pads of paper with pictures and a check-off box for each item. The 2 year old can't write or figure out the 5-in-a-row bingo game, but can help looking for items. It makes the scenery part of the adventure and makes everyone want to keep driving rather than be part of the "are-we-there-yet?" mentality.
We never had all those electronics, and while I feel they have a place, they aren't the only way to go. Participating in group activities is part of the joy of car travel, and individual electronic games really encourage each person to be more isolated.
Good luck!