50-ish, if you find one at 45 or so that you like don't discount it just because of the LRV number. Unless there are standards/color specs involved, LRV is more like a loosey-goosey guideline, not a formula or prescription to follow. And, yes, colors with a higher LRV number have better odds of delivering the light and airy atmosphere you're after vs. darker colors. A dramatically shifting paint color has more to do with its own metameric tendencies vs. the quality of light. A rule of thumb is if your color stays consistent in appearance when viewed in fluorescent and incandescent lighting, it will *probably* be consistent in any light source. More about north light: North exposure is not direct rays of sunlight. Very different from south light beaming into your kitchen almost all day long, or the morning sun bursting through your east facing bedroom windows at the break of day. North light isn’t necessarily reflecting or bouncing off of something else to get inside the space, it’s just that when your windows face north you don’t have actual, direct beams of light entering fenestration. North light is the most balanced from a spectral distribution perspective, it has a nice, even collection of all the wavelengths though it tends to be heavier in the blue range. Because it’s a balanced bundle of wavelengths and also because it is not a direct beaming, or spot-light effect of natural light, north facing rooms are ideal for any kind of artistic work environment. The pronounced blue of north light is a factoid that's been blown way out of proportion. Blogosphere has taken that one single aspect of north light and made a huge deal out of it - I guess because it makes a good 'sound bite' or something. I dunno. But it's kind of a dumb thing to hyper-focus on. Heavy in blue doesn't mean it's gray. Doesn't necessarily mean it's cool either. North light is simply indirect light that's balanced over the visible spectrum as a whole but with a pronounced bump of blue.

My experience is that dark gloomy areas need a strong saturated color. You have to have the lights on when you use this room and artificial light murders lights and whites, so why not do a deeper color? I would paint everything, trim, walls one color so the room is not broken up by distracting trim. Relying on my monitor to make this S.W. suggestion, because this shade of green looks like a good backdrop for you darker sofas and rug. Don’t you rely on my monitor, though…the green/blue in the rug.

You have to look at the color on the ceiling. Light will hit it differently. It is also likely to go over ceiling texture and paint differently, but testing it on poster board or heavy paper is a good place to start. I went through a number of tests before I got the blue for our BR ceiling. And I can't tel you what it was now. I think we might have started with a can from the store and remixed after seeing it directly on the ceiling -- I do that kind of thing. I thing any of those second group and all of the first except the second from the top could look good. You need to pick one that will go well with the other things you put in the room. An aqua can be more limiting and may seem more seasonal.

Thank you @everdebz and @eam44 for the input. I did hire Kylie for a cabinet color consult and she did a good job (though I hadn't chosen a counter top at that point), I was more looking for a cabinet color that would be a "white" that would look good in a north facing room and this is from her consult - "SW Alabaster. This is a warm, creamy white. It will help to off-set the northern light coming in, without being as yellow as Dover White." She also suggested Westhighland White as a 2nd choice. SW 7566 but I feel I see a bit of pink...maybe I need my eyes checked. I do like Alabaster, but it seems a bit too warm for some of my counter top selections. What is the "nuance" of SW alabaster.... And does it contradict what Lori says about nuance below? From reading the chroma info from land of color expert @funcolors it seems I want "Colors with a nuance that is light and clear. Meaning choose paint colors that are clear but not vivid or bright", but how to pick one. Don't exactly understand how I figure out "nuance". Also, do I start with a paint color that will work in a northern exposure and then select a counter top to go with, or do I pick a counter top and then pick a cabinet color? I see so many counter tops that I like, yet I can't figure out how to pick the proper paint color that will work with the counter top AND the north exposure. And then to bring in a dark color for the island. Kylie suggested SW Cyberspace or SW Grizzle Gray 7068. I really like Grizzle Gray, but I am concerned it is too muddied and gray for the northern light. Will the gray stand out more? Say I chose something with green undertones (SW Urban bronze 7048) is the blue north light going to counteract to make these colors appear brown? or will the green tones be more prevalent. Bottom line I am still having a hard time figuring out what the natural light will do to the various paint colors. And because the house is under construction and my cabinet color choice needs to be made, I am not in a situation where I can wait until everything is in place.