This is wonderful how you opened the stairs - you get a real sense of the architecture and it brings in more light. I applaud what you have accomplished. I'm going to assume that the wall above is patched with quickcrete and the whole thing is painted (try to get the wall beyond under the stair too). If you have / want a flat screen, you might mount a swing arm wall mount for a flat panel television on the vertical wall element remaining on the right - just about 3' - 3 1/2' (around 1 meter) above the floor so that it is eye level when you are sitting. The swing arm support will allow you to tilt the television away from the wall ever so slightly across the nearby corner. This can help to eliminate glare from the nearby window and make it possible for more people in the room to view it / expand your seating possibilities. I reference something like http://www.cdw.com/shop/products/Chief-Thinstall-TS318SU-Medium-Dual-Swing-Arm-Wall-Mount-18in-Extension/2555661.aspx?cm_mmc=ShoppingFeeds-_-GoogleBase-_-Video/Monitors/Cards/Projector-_-2555661_Chief%20Thinstall%20TS318SU%20Medium%20Dual%20Swing%20Arm%20Wall%20Mount%20-%2018%22%22%20Extension%20-%20_CIF-TS318SU You can even mount a television tlhat is wider than the wall behind as it can sit flat on the wall and extend beyond the wall to the left when at rest like another plane in your architectural composition. Since the upper stair is just behind, this should be fairly safe for the electronic. Determine precisely where the television will be at rest before you hang the mount itself. Then, look for a low height chest to sit below the television. Ideally a chest with one open shelf near the top to hold your component receivers. You may want to try to run electrical to the remaining vertical wall on the right (the support for the stair landing) to get power into the wall itself, while everything is open. Depending upon where the nearest source is, with concrete walls, you could mount the power junction box low on the wall under the stair and drill out small diameter cord passages through the wall after placement of your components. Or use the baseboard area to run needed cables and power to the area behind the chest, then conceal it with baseboard trim. The more you can hide the power and connection cords, the sleeker the look, to match your gorgeous architectural stair element. If you have a larger deeper television, put it on a sideboard chest under the upper stair where you have the depth. In the rear area, take care with putting cables together in a cord cover - ikea has a good one that is inexpensive. http://www.ikea.com/us/en/catalog/products/20097954/ so it looks "neat" from behind when you come down the stair.

Example below: The wires need to run up behind the wall to the ceiling (see image below). A return was created between two existing walls (you will need to create two columns) - through which you can run the wires if necessary. The screen is hidden in the beam above the painting. In the foreground of the photo is another "beam" which actually contains the projector. It has an access panel again covered in the mesh and there is a flap that can be removed or opened/closed when the projector is in use. US is way more advanced, so I believe other Houzzers can step in...

like so (sorry took liberty with your pic using paintbrush app). in second tv be installed on an island of a solid wall, remaining wall be of glass: use frosted tempered glass for doors n all.. this way you get another expanse of wall to do loads with n utilize full potential (area) of room.. also providing a wall surface on the back of the tv 'island' wall to the sitting area for say a painting, maybe? plus tehre won't be glare on the tv screen either if it's on teh wall-glass partition.. only issue being the slightly longer approach (i-e through dressing room) to bathroom area, which ain't so bad either.. in ur original plan i don't like how a door is sprouting out in the middle of a great expanse of wall... what a waste..

Since the lot you describe is smaller than my open living area, I would suggest looking at some of the "shotgun" house plans around New Orleans,LA. I think you can build up and back and get an interesting home with a loft for space. It can be done, A porch with an entry to a narrow hall at the back might work best for you. Will you plan a courtyard (closed)? or what? What part of the country are you in? What are your local codes?