Recessed cans for sloped ceilings is your ambient lighting; undercabinet is your task lighting. Do you have an island or other work space that can’t be illuminated by undercabinet lighting but will require task lighting? Edited to add that I just reread your OP and saw that you do have an island.

I wouldn't do ceiling lights in this room. I have a feeling the exclusion was intentional at design conception. I think they'd be a distraction. I own and grew up in a MCM. I've visited several others over the years and it's pretty common for MCM houses in our region to not have ceiling lights in the living room. My advice is to move in, get situated, get some table and floor lamps (and lots of them because the days in PNW are mostly gray, damp and dreary - welcome to the PNW!) After four seasons in the house, you can reassess ceiling lighting. You have a jewel. Please remember that furnishings, art and textiles can do wonders to bring in "light". Best wishes!

noise depends on what you mean by open concept. our kitchen and living room are all one room, so I think of that as open concept, but our bedrooms are down a hall. therefore, we don't have noise issues with sound from the living room. when it comes to heating/cooling, it depends on the engineering. how high are the ceilings? how much insulation? how big are the windows and what way are they facing? all of our ceilings in the whole house are vaulted but not super tall (about 11'). we don't have much of an issue with heating in the winter, but the living room is really hot in the summer, mainly due to the fact that it's not in the shade and has big south facing windows (this is Seattle, where it rarely gets over 90 deg). we had 6" of rigid insulation installed under the roof, but it's not nearly as good as having an attic with blown in insulation. I love vaulted ceilings and would absolutely have them again, but just be sure your architect is considering the best when it comes to wall, ceiling and window insulation. finally, other noise factors to consider: we have a metal roof. so that plus no attic means we can hear everything that hits it. rain? very pleasant. pinecones hitting it in a windstorm? SO LOUD. the last time it happened, we barely got any sleep. of course if you have a shingled roof, it won't be as much of an issue.

I would paint the ceilings a bright white regardless of what you do with the walls. The agreeable gray doesn't work well with your tile floors, and you have lots of different grays that don't work with the golds and tans. You can ignore the floors like you have and continue the agreeable gray. Or what about a very soft blush color like your pillow, that would work with both the grays and the tan? Remember that your paint samples are skewed by the gold wall color. Paint your samples in the middle of a white poster board, or prime your walls first.