I'm exploring paint options myself and finding that the media and the display device dictate the LRV necessary for the room. Before I started looking into projectors and screens, I never considered room decor as a factor in light control.
Apparently, it doesn't matter that the room lighting is off if light from the screen is bouncing off of bright colored walls, ceiling, and furniture. A standard beige paint has a LRV of 60 whereas 74 is the LRV of original white - source Sherwin-Williams swatches.
My first foray into a dedicated HT had walls painted black with grey ceiling and red trim. The grey was obnoxious and the trim seemed to glow in bright scenes. I later learned the red trim added red hues to the picture.
I repainted everything midnight blue with medium cherry stain grade trim. The midnight blue was so dark; my movie viewers would fall asleep. So I am back to the drawing board.
Based on new research, I am finding that the screen wall should be black if at all possible. Black shades range from 3-6 LRV. If black is out, the darkest neutral was suggested. A dark ceiling is paramount due to light reflection from the display or screen.
My quandary: wall color. My wife is against a bat cave, ergo no black or ultra dark walls. The most help I've gotten from the net is dark neutral walls with highlights being 1-2 shades lighter. Matte or flat paint and minimize or eliminate reflective surfaces.
You can look at the AVSForum HT photo album for ideas. Many of the photos show the finished room, equipment, paint, and decor. I am thinking you could PM the member associated with the build for more information.