controls
You bring up a good point about the convenience of centralized controls, particularly for an older couple. My Frigidaire 2140 stack is 73" tall with the stacking backet, so the dryer controls are only a few inches lower. I am 5'11" and the controls are fine for me. Someone closer to five feet tall would likely find the controls inconveniently high. I had considered Duets, which can be stacked, but because those units are 40" tall instead of 36" tall, the top of the stack is 6'8" and thus dryer controls are very high off the floor. My stack is in the garage and space is not an issue (plenty of lateral room and depth), the overall height would be a factor. Right now the dryer door is right at chest level, very convenient, but I wouldn't like it six or seven inches higher.