Francisco,
I work with both color and B&W, pretty much equally. However, the styles of shooting I do are very different depending on which I have in my camera. I hate to have to mention PS desaturation, but I do use it as a tool - if I see an image that deserves to be B&W and all I have in my camera is color print film, I'll shoot it anyway, knowing I can change it later. Very rarely, I'll take a photograph with color print film and only later discover that it wants to be B&W instead. Never the other way around.
When I shoot color, it is often the color that matters to me. Bright, festive colors, colors that tell the story. For example, the famous Albuquerque Balloon Fiesta - 700 ballons rising up into the air at once is NOT a B&W event. Same for many of the images of the Southwest US, where I live. The setting sun on adobe strikes fire into it - this is about the color.
But B&W is what I use when the story is about form, shape, texture; or light and shadow. I would use B&W to tell the story of a older person's face, or their hands perhaps. Walls and crevices, stones and fences. These don't have much to say, generally, in terms of color. They are all about structure and shape, etc.
In color, I might take a picture of the roofs of houses, all brightly colored. In B&W, I might take a picture of a shingle on a roof, weathered and beaten.
There is also something special for me about B&W, because I have very bad color-vision defect; I am almost completely color-blind. This makes it impossible for me to use PS as it is intended - color values mean less to me than they probably do to you and most others. I am not monochromatic - I 'see' color, I just don't 'understand' color to any great extent. It's not very important to me, because it conveys less information than it might to another.
B&W however, is very much how I remember things I have seen, how I describe objects to others - in terms of their shape, size, texture, and so on. I would seldom remark on a car's paint job, but I might say something about the shape of the car, for example.
I have tried going out specifically to 'shoot B&W', but I haven't been very sucessful at it (yet). I tend to go out to take photographs, and if I 'see' something that needs B&W, then that's what I do.
I think B&W is very powerful, especially to those who see colors normally. When the color is taken away, the eye needs other cues to draw meaning from the image. Strong lines, interesting subject matter, shadows, contrast, and character all play a part. Focal point and DOF become more important than they otherwise might, because the mind compensates for poor or shallow focus when enough color is present (to some extent). You 'see' sharp images that are not - but not with B&W. So focus becomes a more meaningful way to draw attention to or away from something.
To me, B&W is more spiritual, it has a mystical quality, and I wish I were a better B&W photographer.
Color is what I use when I want to show an interesting picture. B&W is what I use when I want to tell a story.
Does that make any sense? Perhaps I'm just waxing poetic.
Best Regards,
Bill Mattocks