The plane I’m on DFW-LAS was changed to a 777-200 a month back. I originally took 8L for easy on/off and forward facing in either configuration. After reading info here and watching a few videos I moved to 3L. Others noted that the back J cabin has the entire plane shuffling past you during boarding. I’m so glad that was noted, it’s something I wouldn’t have considered. It isn’t as convenient to get on/off but at least when I reach my seat I can settle in without getting stared at and bumped by lots of people and their unruly carryons.