Often it is just the kids and me when we make the 10 hour trek. I'm driving so I can't turn around every ten minutes to get something for them. To solve this problem, I put a large Rubbermaid tub in between the two back seats in our van. That way the kids can reach the toys and they stay much happier, they can also set their drinks and snacks on the table when they need their hands for something else. Occasionally a toy does fall (as you can see, the tub is overflowing,) but S and K know they will have to wait until we stop for gas to get that toy back.
Also on the toy front, we have toys that remain in the car all the time. That way they are special and it is a treat to get to play with them. (Remember, I live on an island where cars are illegal, so the kids only ride in the car about twice a month.) The favorite car toy we have right now is the Magna Doodle. It is a great toy that the kids love, and best of all I think they were $3.00 each on clearance at Toys R Us. Lola the dog and Arial the elephant (our swap stuffed animals) love the magna doodles too.