Your jumping off point should be your lovely blue buffet. Given its style, I thought you might like the ideas in the picture below. You could use a combination of blue and/or creamy yellow. These will work with the grey and white painted downstairs, as long as they are in the same color pallet. Paint cupboards beige or white and add antique bin type handles. Leaving all the trim natural will look nice. Reupholster the seats in your dining room and the 2 stools. Add a hemp rug under the dining table. Place your new buffet on the half wall where you have the two chairs. I noticed the other glassed door buffet in a picture. If it would fit in dining room next to the door, it would be great filled with large bowls and antique platters, etc. If not, place the other buffet there, place fresh flowers on top and a larger picture or mirror overhead. Change the lights so they match (per school room lights in the photo). If you could manage, build in the fridge so that you don't see the side and paint that wall with chalk paint. If your living room doesn't match, bring in blue pillows and cozy throws for the couch. Decorate with botanical prints if you like them and a couple of wicker baskets for the living room. Have fun and enjoy.