TV on the bottom wall. Huge sectional on the bedroom wall and right wall.

Ideally the best placement would be on the wall with no doorways or openings. You will get the best symmetry and geometric balance for your design that way. Good luck!

alternative is TV on right wall and huge sectional on left and bottom walls. Maybe more inviting because you see that comfy sofa as you walk in.

I think I'd use the built-in bookshelves to divvy up the room's functions because that is a huge floor space that neither of them need or really want to share. I'd put the bookshelf built-ins vertically about 1 1/2 feet to the left of the window at the bottom of the plans (really, whatever the distance is from window to corner, duplicate that so the window is centered in the new divided room within a room) projecting out into the room about halfway, leaving a big 6'-7' opening between the two halves. Under the window, put a sofa or two chairs, and you have your reading seating with natural light in the daytime.

I'm on my phone, so this is the best markup I can do for now, but I hope it helps.
For TV, I'd mount it on the wall opposite the door as you enter and have a sofa centered in the opening between the left wall and your new bookshelf wall, or a sectional that leaves a walkway along the left wall, TV either on a swivel wall mount in the same place, or on a console in the corner angled for viewing by all seats on the sectional. Just be sure on that window you have light blocking window treatments for daytime viewing since that's a southwest facing window.