Sometimes, when I get back home and sort through my photos, there are some which I'm tempted to convert to black and white. They seem so monochrome as it is that I assume that it will make no difference if they're changed to black and white.
However, I think maybe it does. The subtle off-white or cream colour tones you get when you leave the photos in full colour give them an extra dimension.
Sometimes, of course, this question doesn't arise.