ml,

I've encountered this at many locations in our home.
We've always tried to paint the transition area with
the lighter or more neutral of the 2 colors. This is
one of those details of home decor that the homeowner
notices a lot more than his guests do.

Besides painted walls, this also becomes a factor with
crown molding, floor molding and chair rails if different
colored stain or paint is being used from one room
to the next. Somewhat obviously, the trim in the
transition area seems to look best if it matches the
trim of the room whose color is being used in the
transition area.

Gideon