"signature floor-through views"

My mental image of a "floor-through view" (as opposed to a "through-floor view") is to stand in a room with a window behind you, look across the width of the building and see out the other side through another window -- the ultimate in cross-ventilation, except that most windows in such buildings don't open.

"Signature" in this context I would dismiss as puffery: they are asserting that they are known for making their buildings like this routinely, and others don't.