I like both those ideas, the whole earth or the cityscape. One of the original cover suggestions was a city layout with each quadrant representing destruction by one of the elements. For example, in the bottom right, you would see the effects of fire, and in the upper left, you would see the effects of wind (sorry to be vague, ďeffects,Ē but the whole project is still sub rosa).
But actually, I think the earth would be best; paired with the reapers, the cityscape might make the cover too busy. And it would have to be a full bleed, else the book would look framed. The cool thing about using just the earth is that youíll have a lot of black space surrounding it, some neutral area for the eye to rest and also room for the title and byline.