Hidden from the road by a thick backyard and weathered wood fences, the 72-room Plage Palace has turn into an inconceivable Cubist-style landmark in the old style Languedoc beach resort of Palavas-les-Flots since it opened last June. The first purpose is nostalgia , and the second is a shrewd wager that the western half of France’s Mediterranean coastline is ready to be spruced up. The guest rooms — all of which have non-public outdoor terraces — recall East Coast summer-house fashion, with shades of sand, oyster, and white; wood-paneled and gray-tile baths are outfitted with customized facilities by perfumer Olivia…