Interior Paint schemes

you might just want to have them the same color as the
walls and ceiling(assuming they are the same)
or have them the same color as the ceiling(if the ceiling
and walls are different)...then you will be able to tell
if you should make them stand out or leave them
integrated with the ceiling...gable trusses stand out
without any distinctive or different color than the ceiling,
yet other times they demand a strong accent because
of other features in the room, or house...try them first
the same as the ceiling and see what kind of feel you
get in the room....additionally, get some arcitecural digests
and power through the pages, you'll find some ideas there, too

Hi,

I disagree... Every cathedral has walls and ceiling different.
Architecturally speaking they are of different planes and can be treated as
such. I am a architect and interior designer and never treat different wall
planes the same. Builders do... so they can spray them all with one color...
but designers want to create interesting spaces.

You can use the same color hue or base color but change to value or the
intensity of the color depending on the light that enters the room.
Cathedral ceiling should be considered a celebration of light... for the
most part you can not see the walls and ceiling  planes at the same time.
And because of light each plane will read a different color or shade of
color.

Have fun and be bold... create a space were life and be inspired and grow.
Sincerely,
Nan