This is all about proportion and I think you're on the right track.

If the beams are too deep, they will definitely make the room seem smaller. The same goes for color; if the beams are stained or painted too prominently, that will make the room seem small, too.

I think dividing the ceiling into nine boxes is good, but I'd make the center box the largest. For example, the outer boxes could all extend three feet in from the walls, making the center box 9 x 15.5.

I plan on painting the beams/crown molding white and the ceiling a light taupe color. Definetely want to add the formal elegance, coziness but don't want to make the room smaller by staining it a dark wood color.

Thanks for the advice..I think I'll go for the center box larger...great idea..

IMHO, I don't like the idea of a larger center box. I think it will make the room look out of proportion, unless possibly you had a table or island centered under the large box. If it were me I would use 2 beams in the long direction and 3 in the short direction. That would give you boxes that are almost square (5'x5'4"+ from the center line of the beams) which I think looks better. A rough way to see what each layout looks like is to take some rolls of paper, cut them to width, and use stick pins to lay them out on the ceiling. You won't get the depth but it will show you which pattern looks best.

I like to install coffered ceiling in master bedroom. I want to know what they use for beam. What type of material and from where I can get. They use regular wood or special lighter weight material they use for beam. Please let me know.