I just flew the BA B744 for the first time in a long while last week and had the choice of an Aisle seat upstairs (61J), front row Aisle downstairs (which has the advantage of not being climbed over) or a window downstairs on the last row (so facing WT+ and possible babies in the front row). I opted for upstairs and glad I did – the aisles are quite a bit wider on the upper deck so it feels a bit more private and roomier, and of course the smaller cabin is great too. I actually managed to swap with someone who was sat in 64K (don’t ask how) which really made the journey more enjoyable. But generally as I say, I think upstairs is far better, even on the aisle. For information, I also flew a Lufthansa B748 upstairs on the same trip – not as good as the BA B744. The cabin is longer so more people (32 people I think, compared to 20 on BA), and didn’t feel anywhere near as private.