If you have enough natural light in your kitchen, white walls will make your upper cabinets “disappear” for a cleaner look so your beautiful blue counters and backsplash can stand out. Blue and white is a beautiful combination. There are so many undertones to white—yellow, blue, pink (ugh!), green… If you want to go that route, make sure you do your research and sample test. The wrong white against your current white cabinet may contrast badly. It’s usually best to match whites against each other or at least be in the same undertone.

You're welcome. I am new to Houzz and I really was just showing you some inspiration photos that I liked or that I thought would look good with the colors you already have. I am not a professional and when it comes to the specific colors I am awful. Sorry. I hope someone else can help with that part.

My trim and ceilings are SW Pure white. I have stained wood lowers and SW Pure white uppers. My walls are a very light gray though so that gives a bit more depth (Drift of Mist). In your case I would probably use SW alabaster on the cabinets as well unless you want the cabinets to look WHITE and the walls and trim to look creamy/slightly yellow. Personally I don't think I'd like the contrast.

I think that painting the ceiling planks white is perfect for your beachhouse, it just needs to be accessorized correctly so that it doesn't look too white and gray (see illustrations below). For the walls, I suggest a light greige, BM Balboa Mist, that mixes well with white, gray, and wood. Or a neutral gray such as BM Gray Owl. Any paint you choose I highly recomment that you paint a large cardboard (available at Dollar stores) with 2 coats of paint (samples available at paint stores) and walk around the room to see the colour in different lights. For your corner fireplace, it looks like something black on the floor under the fireplace, not sure what it is but I would do a black porcelain tile under and on the sides of the base. You can also replace the spotlight on the ceiling by a more modern black one, Amazon has nice ones around $40. Have fun with your project!