Izzie - I don't do a lot of B&W because I find getting a great looking image in colour is much more challenging than doing so in B&W. For the first few years when I got into serious photography, I was pretty well a B&W shooter only.
I remember that I really loved Ernst Haas's work when I was still in my teens and suspect that this is why I was drawn to colour work. Colour in the wet darkroom is much more difficult and challenging than doing B&W prints.
http://www.ernst-haas.com/
As a general rule I tend to go B&W for a few very specific reasons:
1. Simplification - sometimes an image does not work because it is too busy. Taking an sRGB image with its 16 million distinct shades comes down to 256 shades.
2. The "period look" - when I shoot people and places that look like they might have come from the time when photography (or films and television) were primarily B&W, it gives the images a bit of a timeless look. I will use this technique when presenting shots taken in developing countries, where some of the traditions and clothing that go back in time are still in common use.
3. Uncorrectable colour cast - sometimes when shooting in mixed light conditions, the colours are difficult to impossible to correct. B&W doesn't care about colour temperature or white balance, so this is an easy fix.
4. The scene is already highly monochrome. I find that these shots sometimes look better when they are presented as B&W images (and sometimes perhaps not).
5. Night scenes - this is a bit of both a colour temperature and monochrome look in the scene, so more of a blend of points 3 and 4. They can also exhibit a lot of chromatic noise in the sky or shadow detail, but can look effective when converted to B&W, where the noise can enhance an image.
I do find that for the most part, I lose something in the image when I throw away the colour, which is the reason I hesitate in going to B&W shots.