[mickey]

We have in the past, and it isn't a good experience. The seats are usually the really hard plastic indestructible kind, and are not great seats. Also, I think they charge something like $10 per day per seat, so you would be racking up a big charge there.

One option is that most vans now come with built in seats. I would suggest calling the rental car company and asking them if their vans include those. That way, you would only have to worry about one seat, and you could handle bringing one. Just check it with your other luggage.

By the way, I can't believe that you are taking three kids under 4 to WDW with you. Most parents would never do that, let along grandparents. You have a lot of guts, I hope everything works out well for you!