I also have a room chopped up by doors, windows, and my son wants to add a divider. so, I hit "like", hoping to generate some answers for you! It looks like your room is multifunctional. It encompasses dining, television watching, relaxing, and it's a freeway to the rest of the house. What, I wonder, is the most important use of your room? Do you eat at the table? or do you carry a plate off to the sofa and eat there?

Place the tv on the wall where the sofa is. Float the sofa in the room between the patio door and window, facing the tv, arm pushed right up to the wall. Place the chair next to the couch on the stairs side, angle slightly toward the sofa and window. Use a small square end table between them with a lamp; run the cord under the couch to an outlet.

Put the table where the tv was. You can push it to the wall during the day and pull it out for evening meals. Add pretty, large art on the wall where the tv was and use a centerpiece on your table that matches it (and is baby-friendly!) so the table looks like a deliberate part of the design rather than a necessary evil to be looked past.

I agree with the suggestion to move the sofa out of the alcove where it is now. If that's a baby gate at the top of the stairs, the sofa is creating a ladder for toddlers/children to explore the half wall overlooking the stairs.

Bring table down to where sofa is now. Bring sofa up to face TV, kind of where the coffee table is now if it was turned 90 degrees. Chair to left of TV.

I don't understand; which angles aren't 90°? Yes, a proper photo would help a lot and a more accurate floorplan :)