I am known to paint the walls a few times to get the color just right for my poster size photos. After much experimenting, neutrals in earth tones seem to be the most complimentary. It is not true that lighter wall colors are the best. If the room is big enough with large windows providing natural light, the darker shades give more drama and a luxurious feel (now I only paint my bedroom with the darker shades and it adds sexiness).
Below are the shades I stick to by www.BenjaminMoore.com. You can choose colors similar to these by another manufacturer.