You could add 2 tall book shelves to either side of the tv. You can use it for books and other decorative accessories.

As suggested some nice book shelves, or floating shelves on the right side and on the left some photos or art work. If not wanting shelves perhaps a nice big mirror.

If you like a traditional size, you could find two similarly sized cabinets and place them either side for your storage. On top you could hang a number of framed pictures to create a library feel. The pictures would also lessen the impact the TV makes on the room. I would not suggest you go to the lengths of the rooms below, but I am trying illustrate how many pictures can add visual interest.

until you decide why not move the leather chair to the right of the tv to balance out the room

We have pretty much the same thing as you do, with a long wall (16' across) and a large tv sitting on a cabinet centered on the wall. What we're doing to take-up some of that space around the tv, is to frame some 8.5"x11" black and white prints (some of mine and some family images) matted in larger frames, and arrange them on either side and above the tv. It's a work in progress at the moment, but it's working.