Thank you for your input Vicki. I am looking for a light green, and a gray blue for the ceiling. I also love to pick a coral color for our kitchen. I'm hoping that I can make these three colors blend together.

I would just use a bit of the wall color added to the flat ceiling paint to paint the adjoining room ceiling. Go a very pale sky blue for the top most flat part of the bedroom ceiling, then add the wall color diluted with some white to paint on the angles of the tray ceiling. This will show up as different shades of color & really accentuate the different levels. What a beautiful room with the columns & angles around the windows. Are you going to add drapes?

The coral sounds very brave. Just add accent colors in each room from the colors used in the other rooms to unify all the spaces.

If the coral is going to be saturated I would only put a scant amt of coral in the ceiling paint ...... It will gain some coral from the reflection alone.
As for the very very light blue bedroom tray ceiling you might add slightly more tint as you come to the nice architectural elements. I have been doing this for years and love love love it when after being in the rooms awhile people comment along the lines of "is the ceiling slightly blue."? Even my spouse said something after SIX months of LR paint. I think paint is wonderful, forgiving and easy to change. Go big or go home they say!

Thank you Sandra and Pat, I was thinking that the two treys needed to be the same white as the trim in the room and then the blue on the ceiling or would that look to choppy with green then white then blue going up? I like your idea Sandra about adding the wall color with white for the trey. Sounds more subtle and gives it more of a flow. Yes I would like to add drapes in this room from the ceiling to the floor. As for the coral, I was thinking of putting in around the cabinets in the kitchen but if I go with a light green, a grey blue, I need to find something that will flow if it even will. I don't like spaces that look choppy. The kitchen ceilings are huge bare space and I really don't like to fill above the cabinets with knick knacks. I'll never be able to reach up there to dust! Here is a photo of the kitchen. It is an open concept floor plan. I am thinking of hiring a professional to help me with the main living area that is all open with cathedral ceilings and columns.

Here is the beige boring kitchen.

And another view of the kitchen.

Sandra & Pat, I like your idea of adding paint to trim for outer ceiling. When you say add some white paint to wall and paint outer trey, as in cooking....how much would you add? 1/2 cup to a gallon of paint?