What to do with this wall?

A few things that come to mind are giant pieces of art, rugs, quilts or blankets with some sort of design, a collection of crosses or other objects that would have some items low enough to be easily seen. Bet you get lots of good ideas from Hometalkers!

Maybe wood accent, like people do on the eaves of the o of the house.

How about a rustic wood wall? Take a look at these pics. I've been thinking about doing this myself on one of my walls.

http://www.diyncrafts.com/7476/decor/15-creatively-genius-diy-wood-walls

Depending on what is on the other 3 walls, a contrasting, wide trim would visually lower the ceiling. Bright or sharply contrasting coloured abstract art or tapestries would draw your eye up, or even painting that whole wall one or 2 shades off the other 3 walls would make it stand out. Google "feature walls" for other ideas.

I like the idea of birds flying, not real ones of course, siloettes ( oops can't speak) maybe ducks or swallows..

A nice horizontal stripe with paint that matches some contrasting colors in your room.

In addition to the above ideas, you could add a homemade banner; they are very popular right now, and there are lots of different styles you could make to suit your décor....

oh I love those new butterfly displays..... https://www.pinterest.com/search/pins/?q=Butterfly%20decorations%20wall&rs=guide

you have a perfect canvass....look up large wall stencils and do like giant dahlias. make sure if you use a stencil...1) it is secure to the wall..2) use foam dab brushes--bristle brushes can let the bristles under the stencil edges and distort your work...the stencils are not expensive and reusable...use vibrant colors to draw attention to the area

I would run painter's tape from the left to the right just above the doorfacing. Also, run tape along the ceiling where the wall meets. Get a ladder & tape on a stencil. Paint with that stencil & move it over & repeat until the whole area is done. Examples:

I think something abstract would be cool. I make these out of driftwood but you could make one out of branches. My customers have bought them to use in rooms just like yours for that same reason. Buy a glue gun and you can make one with pieces of lathe available at home improvement stores. A bundle of thin lathe is around $15. https://www.facebook.com/Bogtrotterdesigns/photos/a.1350275631671583.1073741835.1221630357869445/1520339281331883/?type=3&theater

Another thought. That tall piece of furniture does bring the eye up.

I think your problem is not the tall wall, but the placement of your furniture. It is disrupting to the eye when the eye has to go up and down. I suggest you move that piece just to the left of the doorway and replace with a nice side table, perhaps with a table lamp. Then above the sofa and at eye level, a very large art piece. It doesn't have to be a painting, it could be a large circular or star shaped metal piece, it could be long and linear. Once the eye catches it, it will stop looking and the rest of the wall goes blank.