Hidden from the street by a thick backyard and weathered wood fences, the 72-room Plage Palace has turn into an improbable Cubist-style landmark within the old-fashioned Languedoc seashore resort of Palavas-les-Flots since it opened final June. The first cause is nostalgia , and the second is a shrewd wager that the western half of France’s Mediterranean shoreline is ready to be spruced up. The guest rooms — all of which have personal out of doors terraces — recall East Coast summer-house fashion, with shades of sand, oyster, and white; wood-paneled and gray-tile baths are geared up with customized amenities by…