You've got two toilets to serve the upper deck. Also the bins give you a sense of space rather than sitting in a coffin and allow you to put your laptop down on to comfortably watch a movie plus room for assorted plates, drinks etc etc...

It is true that for planet watching your probably best in a window (coffin) seat on the lower deck, but then your only a curtain away from the great unwashed in WT+ and (shudder) WT. The stairway to the upper deck gives a greater sense of separation and in the event of anybody turning in to a zombie a la World War Z, the cabin can be more easily defended.

Take the trusty 62K as recommended above...Chris