It is billed as the easiest way to visit New York, Venice, Paris and the Sahara in a single day. But a slick USD 650m monorail linking Las Vegas's famous casinos is in trouble - and its problems are causing a headache on Wall Street. Plastered with Vegas logos, the elevated train plies a route behind the vast hotels that line the Strip - the desert city's main thoroughfare, where tourists can peruse live lions...