Maybe a small side table with a lamp on it? I don't see any lighting if someone wanted to sit and read. Patterned drapes at your windows would be a lovely addition, too.

I would get a floor lamp for the side where the basket is and then I would push the sectional back against the wall for the gap under the window. That wasted floor space is ridiculous. Even with drapes--which I would have--the sectional can be pushed back several inches. Floating furniture only makes sense if you have twice the room for the furniture you have to put in it.

You certainly do not need to fill the space behind the sofa but you do needsome lighting so a side table where the space is in the first pic with a lamp would be a good idea. Drapes would definately be a nice addition and would make that space behind the sofa fell better . I do not like the mirror there I would replace that with a nice piece of art and some pillows with a bit of color.I would like to see the whole space to make any other suggestions

You do not need to fill up empty spaces necessarily. Furniture needs 'breathing room".

The space behind the sofa is fine. However, I do recommend an end table and lamp between the end of the sectional and the wall. If you do not want a lamp and table, then leaving the space open is fine.

It appears that overall, the sectional is too large for the space. If you show us more photos of the room, I might recommend moving the sectional all the way back to the wall or even up toward the tv.

The mirror is not working in that space and, like Patricia, I recommend a piece of art. I would also paint the trim around the fireplace a contrasting color.

Thank you all for the suggestions! Much appreciated!

I really love the idea of painting the trim around the fireplace. I never thought of that.

Here are a couple more photos from different angles. We do have a very tight space and our sectional is quite large. This is our only entertaining space in the house and have people over frequently, so we needed the sectional for the functionality of it.

Accent lighting appears to be missing; your idea of a floor lamp at end of sofa is good. I think an arc lamp would be a bit overpowering--there are plenty of other transitional options--and lots of suggestions from houzzers if you ask. I would also place a small drink table in this space and lose the basket.

Other suggestions:

Move the mirror---it is distracting and not working as others have noted. Perhaps in your entry?

Scoot your sectional further away from the wall---it appears there is sufficient open floor space. Open space is good and will help your room breathe and appear larger.

Panel drapes behind sofa and new drapes of the same on your slider would be my next move. Mount them outside of framing (so inside edge is at the framing) and much higher--almost to the ceiling--- creates illusion of more space in your room. Consider art for between these windows once panels up.

Looks comfy--enjoy good times and memories in your home.

Please move the rug so that it sits under the feet of the sectional.