I would do the chair rail in the same color as your trim (white), and leave the wall all in the brown. However, I am wondering why you are adding chair rail in the first place. With only two walls in the room to begin with, I don't think I would be inclined to visually chop the room up more. Adding crown later would be enough detail to add to limited wall space. I would also think about painting the columns in the same trim color, rather than in the tan, to make them more of an architectural detail that contrasts with the wall color and coordinates with the trim.

Some pictures of the spaces you want to redecorate would be helpful

I own a smaller version of that Ikea bookcase. While I love mine, I think yours is too monolithic for the space. I'm kinda intimidated by all those doors. A lower version of the same thing might work, with more variation in the fixtures for the cubbies, so they aren't all the little doors. Maybe Eket would be a better fit for the room? If you are in Ikea's return span, I think I would return it. Then start over. I actually like Ikea's stuff a lot for contemporary spaces. It can be very creative. I think if you wanted to do Ikea furniture in that space, however, I would go with their upscale stuff. I think it's called the Stockholm series. It also seems you need more friendly lighting in that room. I would have at least one table lamp and one floor lamp. They would also have the virtue of making everything not at the same height in the room. I would choose something interesting, fresh, and less austere to balance out the current linearity. Ikea has many lamps with interesting shapes. Tallbyn? Alternatively, you could think different for a contemporary room. Look forward and think about something like a side table with integrated air filter, or a piece with a built-in speaker. You could very nicely get stereo sound for your TV with a set up like that. Your small table is a side table or for a studio apartment. Larger is needed. Definitely another chair. Think what you want a conversation to look like. As a day to day thing, I would do fewer chairs at the dining room. Remove the one at the end? As is, the dining room is a heavy balance for the living room, and to my taste, has too much out-of-scale furniture.

Your layout is all wrong for this room. Take the maroon leather chair out of this room. It would be better if you had a sofa, but in the meantime, place the loveseat in front of the window, (I illustrate the space a future sofa will take up), the recliner at a right angle from the loveseat and the TV across the far wall. This will allow you to eventually purchase a larger TV for this room that is so long and narrow. Your room requires and 8x10 rug. A lamp on an end table and a floor lamp next to the TV should provide the much needed light for this room. Taking direction from the brick color, here is the color scheme I would suggest for the room. Neutrals leaning toward Gray or Greige with a Dusty Maroon accent color. I might select a black 3D metal object to add interest to the brick without taking the attention away from it. No mirror and no framed art. Your house is contemporary so I would select furnishings that lean contemporary. IMO a light-colored rug with a charcoal or black pattern would set a nice backdrop for the seating. Here are pillows that could be used to bring in the color of the brick. All are from various Etsy vendors. Keep the seating neutral and simple for the room.