Black and white photography is considered to be classic and expressively emotional. After all this time and technology, it remains quite a popular format among all genres.
One of the benefits of previewing and shooting in black and white is the practice of eliminating the distraction of color. Doing so forces you to pay closer attention to composition and texture. Themes such as bare trees, winter, fine art, and a lot of street photography, or the above image of Grand Central Station in New York City, are just a few examples of situations where you might prefer to shoot in monochrome.
Not All is Black and White
Though there are a few arguments for shooting in monochrome, the consensus says it's a process better done in software after the fact. Using the monochrome or sepia setting means the natural colors in the shot are lost. Whereas, if you shoot in color, especially RAW, you can always convert to black and white later and keep your full colored version as an option.
For fun though, make a day of it and just shoot in monochrome. You be the judge.