There are so many wall colours that would work with your neutral furniture, that the first thing to do would be to consider what colours you might want to use in the rooms. Look for inspiration pictures and create an idea book, then use what you like to help you choose rugs, drapes and bedding before choosing the paint colour. Do you have any existing art that you want to use? That could give you clues for fabric colours and style. I wouldn't use the same colour scheme for the two bedrooms, exactly, although I might try to make them look similar by using some colours in common and keeping them in the same style. On the other hand, if you have a child who has strong ideas I'd say let him or her have considerable say in the matter for that bedroom (just this side of reason).

i agree with lighting trends on the peach ,here are a couple of palettes to choose from note your lighting will accentuate the mood and can give the hue you want , but definitely go for a neutral , the colours are from sherwin williams, benjamin moore , behr , and kelly moore

Unfortunately all your options require custom work: It looks like you need an 18" corner cabinet. You will have to modify the last wall cabinet on the left. As I am eyeballing it, you should be able to cut the last cabinet in the middle and then shorten the left section to fit the space of the wall next to the door trim. It's an option that makes the area looks symmetric. Or you can install shelves over the sink. I would not recommend it because it will take the looks away. And the last option will be to remove the last cabinet, shorten it so it fits over the sink and install a single cabinet where the double one was. This will leave a triangle space behind the corner where the two cabinets will meet. You can block the space under it. Hope this helps!

A soft, warm grey shade would look lovely, and can be as dark or light as you want. A warmer shade will work with the brown stained wood floor, and the grey will complement the black granite. You could have an undertone of green, blue or tan if you didn't want a pure grey. And it would look nice with any silver metal hardware, either polished or satin/brushed, so you could choose pewter, chrome or nickel. It would still work with white trim too.