Color choice for "green" screen

Green is a very common color in outdoor settings, leading movie studios to sometimes opt for other colors. This would be a very easy "selector" on the green screen creator.

Additionally for folks like me, it would have a second benefit. I have a projector on the ceiling that aims down at the table with some dungeon tiles. The new magic effects (lightning bugs, etc.) would be AWESOME to bloom onto the table, but I want the bulk of the screen black so that it's not projecting anything else. This would allow creation of multi-layer effects, or even weather effects on a black screen to look like rain falling across the table, bats in the sky, etc. All of these require a black screen rather than green.