Fuselage configurations in which window seats project into and partially occupy inter-frame spaces. In accordance with some embodiments, a frame in proximity to a window seat is equipped with a riser duct closure cover for defining a riser duct for passing a volume of air through a supply duct located below a floor of a passenger cabin through the riser duct and through a crown distribution duct located above a ceiling of the passenger cabin. In accordance with other embodiments, the frames in proximity to window seats are equipped with respective airbags. More specifically, for each pair of adjacent frames in which the forward frame of the pair is located forward of the window seat, the aft frame of the pair is located aft of the window seat, the forward frame is equipped with an airbag.