Ed: Haruo indeed I did leave out the important modifier for the window under seat storage space;
I should have written "That is interesting because one of the "travel" sites that i looked at said the center seat has the most under seat space but the window seat the
2nd most with the aisle seat having the least."
I seriously doubt that they would have permitted you to leave any part of your brief case protruding into the aisle, as the food/beverage cart rolls in that space, with almost nothing to spare.
The two things I dislike the most about flying, are waiting for checked luggage and the mad scramble to retrieve the carry on piece from the overhead. I have learned to stay seated if possible until the elbowing is over. If I have an aisle seat I will let others out and then sit back down. It cost me five min at the most and is a whole lot less hassle. I will not check luggage unless absolutely forced.