1. I belong to the school of thought that says crown molding should be a consistent colour throughout your home. Unless you have a lodge or cabin-type home, painted white, ecru, etc. is usually best. 2. Varying colours of white or varying strengths of paint on a vault or on the tiers of a tray ceiling give it an interesting depth. I personally don't care for tray ceilings that have some of the tiered surfaces or the sides of the tray painted with the wall colour or a contrasting strong colour. Just my opinion. 3. If you're considering painting the walls a darker colour at bottom that fades out towards the top, I can only assume you don't have a very formal dining room, although the dimensions you give would belie that. Your room size is nice and large, and a chair rail would not box anything in---it is really what one expects to see in a large dining room. It also allows you to "logically" paint one colour below the rail and another above. Good luck with your room!

double post

If you don’t get that properly insulated, there goes all your conditioned air you spend so much money creating. Who on earth designed that to not have any insulation???? Paint is the least of your issues when you have structural insufficiencies and need the whole thing rebuilt.

The first step should be to determine and use the same materials...second would be to be clear what it is you like about the colors...at this point any experienced and qualified painter should be able mix or choose the right formula...it is possible to experiment on remnants once the ceiling is done...