Rental car.....will you be using this a lot in Disney? Not sure how Continental works, but I believe you can tag the boosters like a stroller/car seat and leave them on the walkway to the plane. This way they would be put on top of the pile....but ask the flight people at the desk.
Now the reason I ask about the rental car is because of our experiences in WDW. We have a young family so we used to rent a minivan with car seats to get around. What we found was that its just a big pain. getting the seat from the rental place and there generally dirty and broken. Installing them, if there car seats rather than a booster. Returning the car was always a nightmare...because we always run late for our return flight and the line to get back in the garage can be very long. But we discovered once we were in Disney we never used the car, we would always use Disney transportation. So now we book a limo service, not Mears, from the airport to the resort. This service has booster or car seats ready to go. We set a return time and they pick us up at the resort. The last trip we scheduled a Universal Studio day....so the same service picked us up and brought us back....just a thought but I do know many like having the ability to jump in a car and go anywhere offsite. But for us this is one expense not needed.
Brownie