I find a to scale drawing of the whole space is where to start. Then cut out all the furniture drawn to the same scale and move the pieces around until you think you have it done. Unfortunately sometimes what works on paper does not work in real life so a bit of fine tuning might be needed . I think 2 wing back chirs will be a lot larger than 2 MCM chirs so take that into consideration.

I will say thta when you come here with a question you often will get comments you can either heed or ignore but when designers start answering we often see things that need a comment.I will say the DR will be tight even without the leaves You need 36" all arond a table for seating . Your style is not really contemporary IMO so a waterfall counter should poroably not been done but maybe when the space is a bit more finished you can also post some pics of the new furniture choices .

If you want a TV in that room the only place it can really go is to the right of the fireplace (maybe to the left if you find that works better for you). It is never recommended to put it over the fireplace unless there is nowhere else for it to go. You have more than enough space on the right for a nice console. Maybe in the future you can do something more dramatic with the fireplace as it looks small in that large wall (or maybe you are already and it's not finished yet). Put a tall piece of art over it (something that is less wide than the fireplace). Face your sofa toward the fireplace and TV. The dining table should have the long side parallel to the slider. I can't imagine it fitting the other direction. I don't think it's a bad thing to have your old furniture in there for a while. It will help you get an idea of the right size for new pieces. You may also get better advice if you post a graph paper drawing of the space so the commenters know exactly how much space you're working with. The perspective in pictures is sometimes misleading.

@kandrewspa / @Patricia Colwell Consulting - Please note, there was previously room around a table + extension + clutter, furniture, etc. per images below. Yes, it may not be the most space possible, but sufficient.

We do not plan to have a TV in this room. Our TV will be in the family room downstairs. Above the fireplace will be art. In the future, when we can afford to, we plan to redo the fireplace and make it much larger + utilize unused wall cavity to create a built-in, but that’s not feasible right now.

You don’t believe the table would be better off going side to side (so the long side aligns with the kitchen), perpendicular to the SGD - similar to how it was arranged previously (see image below)?

When there were walls in this space before, below is layout. We removed most walls and moved the kitchen to the front / eliminating the eat-in kitchen.