Hi, it's difficult to provide suggestions without seeing the color and style of your living room. Are you looking for traditional or contemporary feel?

Embrace the arches and keep it light, but add some contrast. Paint every wall with an arch in it fresh white, all ceilings too. Paint the adjecent walls a soft color. For example; when you keep the kitchen tile, you could paint the walls above it a soft pink or mauve. I see three open areas, so you could divide those with three soft colors and white inbetween. Keep most lights simple and functional, uplights will enhance the arches, glass pendants will add warmth. And I think a soft olive or sage green is a great color for a living room.

Leather sofas can really dominate the room and can give an overall cold feeling. I would add some earthy elements, like a wood coffee table with glass or metal. Go to Restoration Hardware's website and look at their sofa room scenes. And I'm sorry I think the art is too harsh for the room. That's all your eye goes to in the room. too overpowering. I would look for something softer or maybe a cool mirror and I would add color to the room with pillows and some colorful lamps. I also think woven blinds would look great. They add warmth and give a finished look. The color of your window treatments should contrast your wall color a bit, not match it or else it starts to look generic and blah.. You have warm walls, warm floors and the woven blinds, like Hunter Douglas brand would pull it all together for you.

You need and architect and a designer