I would place the sofa facing the fireplace either with access to what's behind the draperies or not, and put the tv where the chair is--roughly. On the far end I'd arrange a small conversation/reading/activity area. IE:2 chairs, a table and a lamp or a small activity table with a hanging lamp. Of course, seeing the scale of your new furniture, once you receive it will help. I just hope you have selected comfortable furniture in a smaller scale than what you have.

I would use a bookcase unit with closed doors on the lower half and not too high. Wide and low maybe. Closed lower cabinets are great for toys, games and will not clutter. Open shelves tend to get cluttered after a while. When displaying books, use in stacks standing and lying down. Open space between groupings, not all lined up in rows. Add some decor items sprinkled among the books to give the eye a visual break. I would choose a horizontal art piece for the chair wall. Add some art on the long TV wall leaving a lot of bare wall between the TV . and the artwork between the corners of the chair wall and the window wall.

I think your original idea to put the TV on the wall between the sliders was correct. I don't think a TV ever belongs in front of a window. After you move the TV, put the two chairs closer together under the window with a table between them, and rotate the sofa to face the TV. You may have to angle the TV (but not the TV cabinet) toward the seating for viewing, but I think it will be a more satisfactory arrangement for you.

Well the piece above the fireplace really overwhelms the space, and most specifically the fireplace. Is there another wall space anywhere that can showcase it? trying to use this piece in such a small area makes everything else lose its appeal, it has to fight to be seen. For sure move the sofa where it faces the fireplace, or set at an angle facing where you hv the TV set to be mounted. If you can, leave the chair in the same area, use the table the TV is sitting on as a coffee table for both. The way that makes the space work is the way you need it.