The only reason I seperate lower and upper back is because when I think upper back I also think shoulder: hence they are on the same day. My days look like this:
Chest/lower back
Upper back/shoulders
Bi's/Tri's
Legs
As it is, my upper/shoulder workout is pretty long. My 5x5 is on Military Press plus I do 2 more shoulder workouts along with about 6sets of shrugs. After all that I really don't think I can manage another 5x5 set, let alone a DEADlift. I was however, thinking about putting Deads on the legs day.