I asked this over on Home Decorating, but also know the paint experts are here and it really is a techy question. I'm repainting my guest bath a dark navy, presently dark red. The room is small and windowless, but there is a large window in the adjacent guest room which throws light on the back wall of the bathroom.

I don't want shine! I want a flat or matte finish. The present red paint must be flat, no shine at all. The BM man said to use eggshell, but I want to double check with you guys as to how shiny eggshell will be, particularly in a dark deep color with morning light shining on it. No worry about cleaning the walls, it's just a guest bath/powder room.