I see blank wall at top of your sketch between dining room and living room.

What about against the up stairs, close it in.

Put up a room divider between LR and DR, TV on one side, art on the other.

It is an enclosed porch? Lose that window, it is useless.

I'd post measurements so the pros can give you ideas on how to furnish the room. More to it than finding a spot for the TV.

I suggest having a cabinet built with an electric TV lift inside.

Unfortunately that blank space is actually just about 2 feet. Down low against the stairs could work, but it would prevent the area from being used as a benched seating area. Ideally, we don't want to lose the window in the enclosed porch because it would look quite obvious when you enter the porch that a window belonged there. I'll upload dimensions, thanks!

Uploading dimensions will certainly help.

I agree with the idea of a room divider - it does not have to be huge or even completely solid - sometimes all open plan loses the focus or cosiness of a space - you have stairs the other side of room so this will be a natural walk through area anyway, Have room divider coming out of the wall at the top of your diagram? Google room divider for flat screen and you get some ideas - here are a few!