I would suggest adding a window seat on the bay window and adding counter stools on the kitchen island. That would make this area really inviting. Put the dining setting to the right of the kitchen (not downstairs - who cooks and then carries the food downstairs?) and then the living room (with TV) in the room adjacent to the dining. Since you are planning to rent it out to groups of up to 10 people, you really need another TV room. So Instead of having a formal sitting area, make it into another comfortable TV lounge room, but have your furniture arranged in a way that is also conducive of conversation (not just watching TV).

Thanks Gioenne, The clients are thrilled and get many visitors to their apartment to see all the transformations.

Dulux Charcoal on the timber and also paint the orange tiles under the window on the timber side. Too many orange stripes, the other two match so I'd leave them. Paint windows and trim Whisper white, paint the top gutter against the roof charcoal and the trim under in Whisper white. Also paint the door step in charcoal. Like your house, all the different textures just need to compliment each other. I'm building mid century design now, I'm using all different textures too.

Sketch the room with measurements and post here. Pics are good also. You’ll get some great ideas.