THE WINDOW DISPLAYS at Credit Suisse Private Banks headquarters on Paradeplatz, Zurich, would not seem out of place at Saks Fifth Avenue or Fortnum & Mason. Every window sparkles with fairy lights, framing sledges, hats, boots, books, ski poles, trees, snow. Each one has a message. A battered antique sledge: a gift from your grandparents. A pair of mittens: a gift from your grandchildren. The slogan in this window: "A bank that has been with you for 80 years."...