You're welcome! =) I think a shade of grey will be a great addition to the room. The red one in the photo doesn't really suit it. If you have any questions, feel free to ask! angelinavick@ymail.com

This will help get some light into the middle of your space. http://www.westelm.com/m/products/overarching-floor-lamp-antique-bronze-w890/?pkey=cfloor-lamps You could also do end tables or a console behind the couch and place table lamps on either. It doesn't look like you have any seating near the edge of your space and your existing lighting seems to be positioned at the edges of the room. So I'm not sure if sconces would help much.

In order to get comments you really need to offer more info and pictures..this could be a helpful resource if you offer more to work with

I think I am certainly quite late to reply on this post but nevertheless will put my suggestions here. Go for 2 loveseats in a light/neutral colour against the 7 ft and 15 ft wall. Opposite the 15 ft wall you could put a nice upholstered bench in contrast/printed fabric. Also for a warm glow put a nice standing lamp in the corner between both sofas. You can place a nice mirror on the TV wall and put a nice shelf beneath it and place a lamp there with few knick knacks if the door opens outside in the balcony or is sliding. Also, keep two upholstered ottomans below the mirror which can be pulled for extra seating when required. Place a low height coffee table small one like a 2x2 ft.