I would remove the stick decor and get some fun wallpaper for that entire back wall - trees if you like. Lower and tighten up your stuff on the wall. The bottom of all the frames should be level and 5" above the sofa back. Then you can loosen up the items above that footprint, but keep everything within 75% of the sofa's width.

A batten board wall treatment is a thought. If you could bring the wood flooring into the living area that would help.

I love your green metal chairs! Where did you get them?

Chairs are off of wayfair.

http://www.wayfair.com/Office-Star-Products-Bristow-Armless-Chairs-BRW29A2-OT3614.html

Farmhouse style is doable with brown leather, I'm glad you didn't say beach style, lol! I think your rug is small and too contemporary. I would look for something larger, more unique in style. The one in the pic below has an ethnic look, but I've seen some rugs that the weave looks knitted, and some where the weave looks uneven, like a burlap, that would work also. And I love the coffee table in the pic so much. I would replace your ottoman with something wood. You could add some cowhide ottomans to the room too.

Have you thought about putting up a stud wall between the dining room and living room, with french doors and side panels so the space still has a large feel to it but the living room a separate room? Just a suggestion