Here are some pics from Houzz that might give you some ideas. I love the blinds in the first on that hide the upper windows, but it's a pretty contemporary look. The interest on the ceiling along with the chandelier brings it down a bit. [contemporary living room design[(https://www.houzz.com/photos/contemporary-living-room-ideas-phbr1-bp~t_718~s_2103) by new york interior designer David Landy ASID CID NY State This has a strong horizontal element with lighting that breaks up the height: [traditional living room design[(https://www.houzz.com/photos/traditional-living-room-ideas-phbr1-bp~t_718~s_2107) by dc metro general contractor Moss Building and Design [ the last two use lots of wood/built-ins to add heft and interest [(https://www.houzz.com/photos/st-clements-great-room-traditional-family-room-toronto-phvw-vp~81556) [traditional family room design[(https://www.houzz.com/photos/traditional-family-room-ideas-phbr1-bp~t_720~s_2107) by toronto design-build Schnarr Craftsmen Inc [traditional family room design[(https://www.houzz.com/photos/traditional-family-room-ideas-phbr1-bp~t_720~s_2107) by atlanta interior designer Mary Trantow

My kitchen cabs are maple and my granite/floor are gray. We painted our LR in BM London Fog and I like it alot. Our accent colors are gold/tan, but you could pick a green that goes well with whatever gray you pick and do accent walls or other surrounding rooms. In my case (center hall colonial) we did the foyer/stairs/upstairs hall in a light gold/tan. The kitchen is a darker version of the gold/tan. The LR is light gray (London Fog) the DR off LR is 2 chips darker as is the FR--Plymouth Rock. The powder room is on same chip but darker--Waynesboro Taupe. I kept all the ceilings white as well as trim. I felt daring doing accent walls/different colors on same floor, etc...but it coordinates and came out great...I love it. Maybe start with the green in your chairs and then go around the fan deck and find a coordinating gray.

As others have pointed out a north-facing room will have no direct sunlight and little natural light 365 days a year. The good thing about north light, as any architect or artist will tell you, is that the lighting level and color will tend to be the same throughout much of the day, i.e., you will never have hot spots, glare and significantly different lighting levels throughout the day. If it was my house I'd find a cream, white or other light value color to enhance and amplify the overall light level level. Creams and whites come in a wide range of hue and temperature biases. I always recommend that consumers buy several of the small sample containers and do "brush ons" on several surfaces which are parallel and perpendicular to one another and to the windows, since colors always look different depending on where they are located. They also look different depending on whether the day is sunny or overcast. Good luck with your project!

Don't have time to answer all of your questions but here's what I can suggest: 1) Lower the mantle on fireplace a little, as well as the painting in the niche. (See #2 here) Consider changing the mantle to something less rustic and paint in color A (see next suggestion) 2) Open spaces should be cohesive - which you can easily do with paint. Choose 2 colors or 2 shades of the same color and vary placement in different areas. (see #5 here) Consider adding a simple chair rail to the dining area. For example, with minimal effort, you could use color A below the chair rail in dining area, as the dominant color in window treatments fabric (I"d use draw drapes) , the back wall of niche, throw pillows, lamps ac, and maybe an area rug in living room, and in accessories (see #3 here) in living room and kitchen. I'd consider adding some of that color to kitchen also -- back of open cabinets for example, recovering bar stools and dining room chair seats to match drapery fabric and possibly slip covering one of the armchairs in the living room in a pattern that incorporates the wall colors with other colors in the space. You want to use coordinates, not just the same solid everywhere so look for different textures or patterns to add. Hope that helps. I've inclluded links to additional info about topics I mentioned that I think you'll find helpful. 3) see #2 - I'd choose lamps with either a base or shade to match color A. (See #7 here) 4) Add plants. If you aren't there often enough to take care of them, use artificial greenery.