Upholstered Cornice

Often to hide drapery hardware, or simply for decoration, cornices are decorative boxes added as an extra touch to window panels. 

Here is a sample I found online:

I have been thinking for quite some time of doing this in our family room.  I wanted to bring some more pattern into the room and thought it would make my room feel taller by drawing the eye up. 

Here are the windows in mind:

 

I was thinking of using this fabric -

I am not sure if I should do a solid with nail head trim like the sample pictured above and use this fabric for more pillows, or use this for the actual cornice.

I would love to hear what you guys think...???