A nice whitewash wall/paint treatment would brighten it up if done in a light color. Or I would paint it but not sure if all the knots will bleed through? If so then I would use an oil base Kilz to stop bleed through and paint it depending on the interior design I want for each room. I would not paint the ceiling for a more Montana look,

You can of course have a furniture repair business add material and refinish. Or you can add a center accent piece of tile, or wood inlay. If you're going from a narrow rectangle to a square, you would need to disassemble the table anyway, might as well do something fun with it.

Thanks very much for all your feedback. Just to answer a few queries - the deck is directly outside the main room so the new doors open out onto it. The doors won't be French - they're just the only doors that the 3D planner I'm using had, they'll actually be large stacking doors. I've had another idea too which would be a lot more expensive but offers a completely different approach. This is quite rushed so doesn't show accurate layout of kitchen or anything like that, basically just provides an idea. Thoughts!?

Oh my gosh!!!