Pretty much all your art is too small.
With that large TV, the only other arrangement that might work is to divide the room in two by putting the TV in the nook with sofa facing and a chair on one side, then have a smaller seating area by the fireplace.
If you keep the seating like this, a bookcase in the nook is a good idea.
Good places to look for art:
gallerydirect.com
greatbigcanvas.com
art.com
Wait for sales.
Q