As someone that has done DXB-ATL several times, unless you are planning a few months ahead, it will be really tough to upgrade, or get a window or aisle in EC. This a very heavy route for Expats working in Iraq and Afghan that fly this route 4-5 times a year and have status. I usually buy an M fare 60-90 days out and am always wait-listed, but I always make it to BE. I might just start buying a J fare, instead of taking my chances?