Most of my favorite landscape photos include clouds, mainly because they add drama and draw attention through the scene. Here in New Mexico we are known for predominately cloudless skies; but when the clouds appear, they are usually spectacular.
I seldom take pictures only of clouds, preferring to find an interesting foreground to add balance to an image. Typically, on a hot summer day when the monsoon clouds are building, I will start looking for locations with good foregrounds to build composition. I have scouted a few areas in anticipation of a time when good clouds may appear, and have had some luck at this. The villages of Galisteo and Cerrillos are a couple of my favorite locations.
I have been lately trying more abstract foregrounds, thinking about letting a dramatic sky have a more powerful role in the composition, and letting the foreground act as more of a complementary element.