|Nice work. I wouldn't agree that all landscape work should be in B&W however. B&W works better for subjects with good contrast and a good range of tones, and color works better where you can take advantage of 'color contrast'. In your original group, 'Liquid Rock' is very nice, though I would have recommended looking at the histogram when you were taking it - undereposure would have allowed you to hold the clouds.
Recently I'm favoring B&W myself, but I've found that you have to plan for B&W in advance (and look for suitable subjects) to get the best results. The image below was planned for B&W because I knew I could later play around with black and white levels to introduce some drama...
On the other hand, the image below doesn't really work as B&W (I once tried) and was anyway planned to get the most out of those gorgeous late evening colors...
So, by all means, experiment with B&W. I do recommend looking for suitable subjects though and making your B&W v. color decision before you take the shot.