Perhaps if you simply brought the sofa out of the corner and into the center of the room, your space would feel more balanced and you could place some bookcases or a nice credenza along the wall for display & books.

I agree with bepsf, move the sectional, I would also think about a bookcase placed between the two windows. I also think the rug needs to be centered in the room, not centered on the furniture, (hope this makes sense) makes the space look small.

I agree with the comments above.also move the huge picture to the wall on the right coz it appears a bit crowded there.You could also paint the room a lighter colour of the same hue and maybe some indiscreet lighting would give a cosier feel to the room

Remove the artwork from the wall of windows. Put a framed mirror on the wall across from the fireplace.
I agree with amyruth6 pull the sectional out from the corner.
Bookcase in between the windows with the lamp on top. Center the rug and place the "ottomans" in the center with any accessories you may have...