You have done a beautiful job of tucking plants into the crevices of your retaining walls. Your house trim color is perfect -- just slightly lighter in hue than the retaining wall blocks. First I would paint the big, flat gray wall slightly lighter than the blocks and slightly darker than the house trim. The concrete walk and stairs I would stain a mottled blend of the blocks and the house trim colors. Next would be to paint the railing black or the house body color. Now, think of the following as creating a light, airy trellise structure from the walk-level face of the (currently gray) wall to about 7' above the top of the wall (using 6x6" posts attached to the wall) with a corresponding line of posts sunk into the terrace level 2' in from the outside edge of the wall-attached posts. The inside posts would be about 6-8" higher than the outside posts. Put 4x4" wood to attach the outside line of posts to each other and do the same with the inside line of posts. Run wood pieces at the top of the two lines of posts from the inside line to the outside line at about a 45 degree angle. They would be cantilevered up at the terrace level. Across the top of the angled pieces create your top trellise boards which run parallel to the two lines of posts. OK. There you have your basic structure. You might want to extend the structure around to follow the street side of the terrace. You could then follow the suggestion of reom10 above about creating a bench-planter on the terrace side. Your spacing of the boards parallel to the gray wall and attached to the outside posts would determine how private you wanted your terrace to be. You might want to soften the terrace "floor" by using something irregular like flagstone with groundcover plantings between the stones. From the latticework on top of your structure you could hang seasonal flower baskets. Plant vines to go up the trellis and spill down the wall. How about planting a row of tall, narrow shrubs along the neighbor's fence above your terrace to help add to your privacy and make your yard feel less 'structured'? Or, how about patio table/s with umbrellas to block your neighbor's view? Anyway, you have a fun project ahead of you.

Thanks for posting new views of your room. You are right, nothing can go in front of the paneling, and we won't block the built-in cubby. In that case let's work with the rest of the space. I found a picture on Houzz for your gallery wall. I think this will allow you to bring in color and texture and interest to your wall without taking up space like furniture would. Try to play with portraits and a couple of paintings in there too - mix it up. Otherwise I would not put anything at the top of that landing (I'd remove that console table). That picture wall should be enough visual interest to your space and it'll draw the eye to the furthest wall as you walk in your house. I would try a small piece with closed storage between the bottom steps and that door by the entry. It looks like the space is no wider than 26", so it'll be a challenge to find something that fits and is tall enough. I would not use the wooden piece you showed above because you want wider proportions and fairly narrow depth so you don't bump into it as you walk by. (something like this ) I would hang a mirror on top of primping. By the cubby you could add a single seat stool. I'm not particularly suggesting these colors for the stool and bombe chest but something along these shapes. At this point if you do that big picture wall and add these two pieces of furniture and a mirror, you might not need to hang anything on the wall above the cubby. Also, I noticed your chandelier is quite substantial for the space and hanging pretty low. Would raising it a little or replacing it by something a little smaller be an option?

@kmkane... The "old thread" comments, at least from ME... aren't for any other reason than letting some contributors know, that the advice they might believe they are giving, may be moot. I know that when I 1st became involved on Houzz, I was glad when someone indicated that I may be addressing a question which had probably been answered months (if not years) ago. Helped me "learn" to check the original posting date before blathering on about an issue someone was no longer interested in.

I would suggest you take out the cabinet that is to the right of the stove and use it elsewhere in the house -- perhaps in the bathroom or dining room with a hutch above it. Then, I would suggest you have someone install a lazy susan cabinet in the corner between the sink counter and the stove, meaning you would move the stove down a bit and have a small cabinet/counter top to the right of the stove. I would suggest you have the cabinets refinished in white and then paint the walls a pastel you like. If you would prefer white walls, then add white-painted crown molding and paint the ceiling a light neutral blue, such as Sherwin Williams Niagara Falls Blue. Then, I would suggest you choose a favorite accent color and use this sparingly in accessories like towels, pot holders, small vases or floral arrangements, and a valence above the triple windows. For a genuine 1940s look, you might have white ceramic square tiles with a rectangular red border installed as a back splash behind and above the stove. If you are replacing counter tops, I would suggest a light color such as white with a beige or light grey vein or striation for some sort of pattern. You might be able to find the same color and design in floor tile OR opt for a wood floor as another poster suggested.