Actually we've stayed at some of the WDW deluxes and frequently stay at the S/D. We've found WL and BC rooms to be smaller than S/D rooms. We have brought an aerobed to all and we had to move the table and chairs to set it up at WL and just had enough walking space.
I think there is more room in the S/D--a rollaway or aero can be set up along the window area so it's not in the way. The area long the window/slider is definitely not wide enough at the WL or BC rooms we've been in/