Lower right. You don't neccessarily have to have all 4 feet of sofa on the rug, but you should have at least the front 2. You'tt probably want a more durable, washable rug because of it's location at the door. Best length would have to be judged based on door location and some sensible distance from TV -your 10 - 20 cm? Out of curiousity, what is the white box in the upper right of the room? Is it movable? If it is, it looks like your sofa could go on that wall, and a light chair (or 2) where sofa currently is. Then the area rug would be centred on the sofa, the chair legs might not be on it, and rug would be away from the patio door. Is that any better?

You have a lot going on texture-wise so I'd probably keep it simple in terms of rug texture or there'll be too much going on at once. Warm would do well in this room though, so that's good! You mention it's away from the light outdoor area, is this photo an accurate representation of the lighting you normally get in this room? So in summary, you might want to have a look at rugs that don't have much texture, and are a bit brighter in colour to help brighten up the room. Below are just a couple of examples of rugs that could work, and one more neutral example.

there is also a difference between ceramic and porcelain tiles - often these issues come down to a combination of (a) tile batch size/consistency (b) tiler's skill/capacity (c) communication in that if the tiler opens the tile box and he can't practically achieve what he thought he might because of the general discrepancies in size then they should at least speak to you before they start. So often with many issues in this game, it's about managing people's expectations and having open/honest discussions at the right time. When this breaks down, problems and disappointment is more likely to occur......so coming back to it, if you have high quality porcelain tiles that are millimetre perfect, square and flat then the capacity to lay them with minimal spacing is higher. Also the substrate/prep plays a part as if it's all out of whack and not perfectly straight/plumb/square then you'll be in all sorts trying to achieve the minimal tolerance detail.

Hi, I would do a bigger lounge rug, one that extends to the base of or under couch but stopes similar to current in other directions. I’m not a fan of dining rugs as diff to keep clean and get fouled by chairs. I think you need to look at the dining room furniture, both the varying styles and placement, it does not appear cohesive. At moment putting a rug under table could help bring the attention to that area. Changing or moving the other furniture and dressing table may help that too.