This is the mock-up.

I think your inclinations are correct. The blue will feel too dark and make the room seem much smaller. Also there is the issue of the wall base, which likely transitions into other rooms, making any color wall clash in an awkward transition. I'd stick with white walls and bright colorful artwork to punctuate the space.

I painted my living room a grayish green but it was so dark I had to repaint the largest wall a light orange to add lightness to the room. I'm thrilled with how gorgeous the two colors look together, and love how they warmed up the room.

I would start by painting one or two walls and see if you like how it looks. The worst that can happen is that you don't like it and have to repaint.

Some shade of blue may be beautiful, but not the shade you illustrated. Too deep, too bright. That color is usually used for accents, not wall color.

I love your ideas, but your tones all add up to too dark...See what happens when I turn your room to black and white: it is too heavy on the black.However, I think your idea of painting around the window a dark colour a great idea as it offsets the light perfectly. I would also consider painting the wall with your TV on it a dark colour as the TV will not stand out and the other side a lighter colour where you can hang a large painting or artwork above your sofa.My feeling is, if you want to go for blues, go for an ombre teal blue which would add visual interest and additional height and also negate the closed feeling...