Windows that are taller than they are wide and raise
and lower are often better suited for horizontal window
coverings, while windows that are wider than they are
tall and slide from side to side are often better suited for
vertical window coverings.

You may also want to consider horizontal window
fashions because they can enhance a room's
informality and coziness. On the other hand, vertical
blinds or privacy sheers, which are constructed of soft
fabric vertical vanes, can add height and dignity to a
room.