AH, SLEEPER TRAINS. Meditate for a moment on those relics from the golden age of travel. Imagine yourself scuttling over the Alps at twilight, listening to the rattling of bone china, the clinking of whiskey bottles. Now picture yourself wedged into the middle of a packed airline cabin, hearing the blare of the engine and the snoring of your seatmate. Is it any wonder that night trains are back in vogue?