Have you considered some of the oversize art pieces from Z Gallerie? They have some that are 72 " wide. Also, try the Loft collection on art.com. I belive they start at 60" and have many in the 72" and 84". Would be less expensive than Z Gallerie, but with that goes quality of the piece. It's a great room, nice blank canvas!

I found some really awesome paintings on Etsy which are that large.

Can I put the TV in the middle (on top of the console) large painting on one side, and plant on on side (the plant would go on top of the console) or would that look too assymetrical?

It's difficult to tell measurements from pictures but you said "large sectional" is the rug large enough for the front of the sectional to sit on it? I would get a console that is about 75% the width of the wall, center it and center TV on it. Then get coffee and/or end tables and lamps situated before worrying about wall décor. I would get art for the wall with the opening but I don't care for the wall around a TV decorated

I wouldn't put large art on the TV wall. I think it will make it look unbalanced. I would either put shelves on each side of the console or use smaller art pieces to make a collage around the TV. Large art on the side wall.

You should consider breaking the wall up with an oversized floor mirror that will help add depth to the room. Open ended bookcases would also help break up the walls without feeling too heavy. A bookcase like the one pictured below from Crate and barrel could help because they are versatile so you can make the span as big or small as you like.

Start by getting a larger rug. Sectionals are space eater that never give as much seating as you think the should. Unless two people are willing to interlace legs, there’s no corner seating.

if you search how to decorate a TV wall, you will see that there are floating mantels available now. They come in gorgeous cuts of wood and allow you to break up the space like a conventional mantel and fireplace wood. Usually people put their art and photographs off to the side of the mantle and the mantle is usually slightly offset from the TV. you could probably fit a pool table in there and an old arcade game as well.

*would*

Corner seating is the best seating. Especially if you have children. Don't let anyone tell you otherwise.