A seat cushion should be as thick as a sofa's (2 to 4 inches). Additional 20-inch-square firm pillows lining the back offer more support, as do soft throw pillows that can be tucked behind the small of your back or your head.
Augment natural light with recessed cans in the ceiling, sconces on side walls, or a table lamp on a shelf (shown at left) so that it's easier to read or jot notes at your seat. Use dimmers for energy-efficiency and to create a soothing space for napping.
Not just for curling up with a paperback anymore, window seats increasingly are places where people plug in a laptop. Outlets also let you easily charge an e-reader or a tablet without leaving your cozy perch. Tuck them into the toekick or side walls.
To prevent glare or heat gain from the sun coming in through windows, add shades or blinds, which can be chosen in materials and fabrics to complement the room's furnishings. If the window seat is used for sleeping, consider installing drapes in front of the seat to conceal the entire alcove, creating a room within a room.