I was searching for a matching chair to use in my living room and I found your page displaying the same sofa that I have! I purchased this early last year and it stayed wrapped up for months until my construction was done. I really like how you're already tying in the neutrals together. This sofa is so versatile, I have already done an updated xmas scheme and I am about to change around it for spring. So I would say if you must tie in together more than use a solid pillow or two, and or solid throw in either color.

First ,is removing excess furniture an option? Second, why bar fridge in the dining area, that really ruins the look. Seems that you can not move dining table closer to the kitchen because you have light pendant above the table, so can you move piano where your black couch is and couch on the other side of the room instead of creamy colour sofa . I notice the luck of coffee tables and side tables,that's probably why you like to sit around dining table, it is not visitors friendly and doesn't encourage conversation or interaction. I will come back to it have to study photos more. Are the arm chain the other room similar colour to the couch in the dining area?

Go with your plan to feature colour Wall A and mount mirror on Wall A and place beachy art work on Wall B. My suggestion is to maybe consider using a paint colour for the featured wall that is tonally similar to paint on Wall B and not too dark so as to give room depth but not close it in with a dark heavy contrasting shade. Offsetting the hanging of the mirror closer (to the plant) could also add interest (and work with the shorter end of the sofa). Often going with you intuition is the best advice!!!

Ok, I see ...one possibility would be to retain the unit as shelving where it is and wall mount the tv on the adjacent wall so that you can optimise seating arrangement. Otherwise I think you are on the right track, a circular rug would work, maybe a couple of mid century chairs might look nice, you could put some trailing plants up high away from your little one, maybe a basket or two to keep toddler clutter in check would go with an eclectic kind of look. If you move to a larger space in the future, mid century chairs would be easy to pair with a couch.. I think try and bring as much storage as you can to keep the space manageable.