As told by other beforehand as well it is impossible to prebook the exit row even with an elite card. Even more impossible when you are on a DL coded flight.

At the airport they actually do seem to consider height for exit rows. In JFK last week for my CDG flight they wouldn't give me the exit row at chk-in. At the lounge they said they hold them for tall people and asked me to check closer to departure if they were still free. I did that about 90 minutes before departure and the lounge attendant then called the gate and said something like (he is of normal height), then I got it. Middle seat in it was left free and the man by the window was really short (!). Soon after boarding completed a poor guy with _very_ long legs came up and sat between us. I don't understand how he managed to get stuck in a normal seat if height is a consideration..