Look for a vintage set (table and chairs) in a wood tone similar to the top of your dining table. I think that would lighten up the kitchen and yet connect with the other rooms. I would get backless stools for perching, remove or lighten the shade on the door and find a more colorful rug for under the kitchen table or even paint the base of the table a bright turquoise or apple green. Can't quite tell what other colors you have as accents.

I see a few things that aren’t horrible, by any means, but could be changed. Mirror and sideboard, for instance, as mirror is too large for the sideboard and it overwhelms the room, reflecting the t v. Try the art over the sideboard and add a floor lamp where the plant is, as it will do double duty for the sofa and the art. Have you ever thought about adding a floor to ceiling strip of trim to separate the dining area from the living area and painting that wall a color? Something like this with a couple of white shelves on that wall?

A round table large enough to seat even 8 people would make it almost impossible to get additional seating in the room. Plus, a 72" round means that people across the table from each other cannot converse because they are simply out of range. (a la banquet tables that usually seat 8). I have included a seating guide go give you an idea. Your idea of two 72"x36" tables has the same liabilities and more if you choose a table with 4 legs at the corners because someone would have to staddle a leg at each "end". https://www.countrysideamishfurniture.com/blog/entry/the-complete-guide-to-dining-table-seating-capacity I heartily agree with suezbell who suggests trying all this out for yourself with graph paper and furniture cut outs that are done to scale.

Beautiful. You might consider an awning over your patio door. https://www.ebay.com/itm/40-x-80-Door-Window-Canopy-Patio-Awning-DIY-Overhead-Door-Clear-Decorator-/192387040987 Especially like the materials you used for the steps and landing/patio as well as including the fountain/bird bath but do take care not to decorate to the point of adding clutter your space. Potted plants flanking your door could add a welcome vibe. You might add other plants and/or wind chimes with posts that can be mobile: a wide holiday tree stand can also hold a4"x4"x6' post for hanging brackets and solar lights to be put where you want them when you want them. Since you have multiple sections in the southern sun, you might consider which one you could add the shade of a pergola over it (or gazebo by it) without blocking the sunlight to the other sections (likely the western most area) and decide if a small pergola or gazebo would suit your plans for the use of the patio. While cushions could be stored out of the sun when not in use, as you choose your furnishings, so please remember that the southern sun will bleach/fade the color fabrics and even furnishings such as wicker whereas your black metal furnishings could easily be repainted as needed so you can avoid making decisions you might well regret. Even if you prefer new furnishings for your summer use of your patio, your metal furnishings could be repainted and set in another, perhaps shady, area of your yard with their legs on individual pavers with their tops at ground level. Your view from your patio will matter so consider what you can do to improve any areas you might prefer looked better even if it is only adding a green hedge visual around the edges of your yard. Pick shrubs that will look good year round. If you are in Zone 7, consider Aucuba or Camellia or the type of Abelia bushes that keep their leaves year round and provide color and/or blooms. Looking forward to your after pics.