I love love love color and was determined to use it in every room when we first bought our house. But it was a real challenge to find the right balance. After painting each room 2,3 or more times, we finally scaled the color back a bit and ended up with RL Gold Finch in our kitchen. It's a sunny color, very much like the yellow in the picture from RMS. Our walk-in pantry (formally the laundry room) and 1 wall in the hallway is Behr Grass Cloth which is a close match to the green in that same photo. We originally tried a beige in the living room, but it opens into the kitchen and I didn't care for how the Beige worked with the yellow, so we opted to go with an off white called Behr Raffia Cream. It's on the 3 shorter walls in the living room and on the 4th wall located away from the kitchen, we used Behr Warm Muffin which looks like a darker golden color. That wall is very large, has a good sized window as well as our front door, which is painted white. It also extends up into the stairwell and it's all the same Warm Muffin color. It works amaziningly well with the Raffia Creme. We originally had a copper color on one wall in the living room but just couldn't adjust to it, it was too strong. My favorite part about having the colors that in the morning our whole downstairs glows in the sun. It's a great way to start the day. That kitchen in RMS is amazing, oh boy don't I wish I had the talent to mix and match colors like that!

If you have lots of art try some on either side of the fireplace, remove that mantel and get one in a wood similar to the table and add some proper trim around the fireplace. The mantel is too high to do much for decor. It seems odd to have the fireplace in this narrow DR was it something else before ? Some nice window coverings , remove the stacked tables in the corner and the clutter from the ledge.When doing the art just keep working at what works well together and I would google how to hang multiple art on a wall.I don’t love gallery walls but sometimes they do the trick if done right.

Move the clock to a lighter room, pull the sectional away from the windows a bit more, and place a wide, low table or cabinet beneath the windows. Decorate it with a few striking items -- something metallic (a tall silver vase?) would help, in particular, to draw attention down from the irritating roofline. Keep the shapes bold and simple to show well against big white squares. If there is also enough space and light for it to thrive, you could consider a tall, narrow plant to the far left of the wall.

@Mike - Yes it comes up from the basement. I’m open to moving the vent upstairs as well, but my understanding is that it doesn’t matter in regards to how it will operate upstairs. The issue is that right now the HVAC is a straight shot up, so creating that initial turn in the basement is what is going to impact the efficacy. @June - that is interesting and gives me pause. We have a master bedroom/bath addition that was added over the garage in 1950. It has its on HVAC. I wonder if we could simply hook the whole upstairs into that unit.