I have my older 2 in the very back, they can walk to get out of the car. DD3 will probably go on the right, because I can easily park so that one side is easier to open the doors on, because half the car parks are too small, and if I am getting out on the right (as you do when you drive) we will mostly be using the right hand side to get everyone out. Roadside parking up here is MUCH wider than most shopping centre car parks, so I am not likely to have issues with the door being out in the road!!