In my opinion, a cuckoo clock is a very detailed design, but you say you want a simple design for the room. When you say simple, are you thinking of no wallpaper, no wainscoting, and no accent color on the walls? It seems as if dark orange is a color you favor. I see it in art images and in your curtain color. If this was my space, I would paint all the walls one or two shades lighter than the beige of the sofa to keep the room as bright as possible because the room has no direct sunlight. I would paint the ceiling 1/4 (one part wall color to three parts white). I would use a satin or eggshell paint instead of matte, semi-gloss, or high-gloss paint. I see some discoloration on the wall behind the sofa where the brown color of the sofa frame has worn off onto the wall. I suggest attaching bumper dots or strips on the wood frame of the sofa (similar to the ones used to keep cabinet doors from making a lot noise when they are closed quickly). I would consider painting the sides of the column with the cuckoo clock brown to match the clock. I would do this to call attention to the clock. I would remove the orange curtains and replace them with floor-to-ceiling length draperies hung as close to the ceiling as possible to make the room seem larger and taller. I would change the drapery color to match the walls, perhaps in a muslin-like fabric, which is a casual fabric. I always take my art to a professional framer. I have conservation matting and museum glass used for my art. I would have the three images you have rearranged as a collage in a very large single frame with medium to wide matting between the images. I would have the mat and frame color(s) enhance the images, even if it is a color I might never have thought of on my own. I would hang it above the sofa. I would use the orange drapery fabric to make throw pillows for the sofas. You did not attach a photo of the flooring in the room. A medium tone floor is easier to keep looking clean than a light floor/rug or a very dark floor/rug. Other "Houzzers" will give you completely different ideas. Use the ideas YOU like and enjoy your home!

There is contrast between the traditional furniture and the focal point of the floor which pops, draws attention. I would recover the sofas in cream colored soft fabric - suede. I would leave the curtains grey, and put down a large neutral area rug. The edges of the room would show the pattern of the floor. I would color the wall and add texture to it, but not too dark as the room will appear smaller. Add a picture and put a nice plant holder, large vase in the left corner of the room - an oriental-style vase. Or, a cream-stripe fabric on the sofas. You could go soft or bold in this room - depending on your taste.

How do you decorate your place, what kind of style, colors, and feelings? That will greatly influence the type of door you might want. Also, think of your budget, and whether you want to install it yourself or hire a professional (you don't need to tell us, just keep that in mind). Then look around Houzz, in the products page, they have lots of interior sliding doors and hinged ones, from elegant frosted glass in a dark wood frame, to rustic reclaimed wood planks. You may not want to purchase that exact model, but it might give you a better idea of what would fulfill your airflow needs without sacrificing style.

There are so many wall colours that would work with your neutral furniture, that the first thing to do would be to consider what colours you might want to use in the rooms. Look for inspiration pictures and create an idea book, then use what you like to help you choose rugs, drapes and bedding before choosing the paint colour. Do you have any existing art that you want to use? That could give you clues for fabric colours and style. I wouldn't use the same colour scheme for the two bedrooms, exactly, although I might try to make them look similar by using some colours in common and keeping them in the same style. On the other hand, if you have a child who has strong ideas I'd say let him or her have considerable say in the matter for that bedroom (just this side of reason).