Are you buying new furniture? I think the placement of the fireplace is wrong because it should be a focal point around which you can arrange furniture. That's not possible with the stairs in the way. I think it should go on the wall where you have the sofa. Sofa at the windows where the tree is with the coffee table 12-18" from it., and the two pictures stacked vertically in the spot where you have the fireplace now. Center them at 5' above the floor with one hand's width between them. Lower the other picture to center 5' above the floor too. Look for an area rug that is at east two feet wider than your sofa. Add a pair of chairs at the stair railing with a table and lamp between them. try the round mirror in the dining room to reflect/double the light fixture..