Compared with the published title, in spirit I have to go with JV on his more elaborate preference (publishers and their lackey editors are overly concerned with practicalities, such as cover display, advertising, and sales reports, all of which suffer from a very long and enigmatic title). While of 18th century length, it does set the scene for the story. Big Planet is a lot of things, which cannot be characterized as "the world of showboats," whereas the Lower Vissel, in Lune XXIII South, does fit.