CANCUN, Mexico - On a neighborly sightseeing jaunt Thursday with the leaders of Mexico and Canada, President Bush said the three were working to improve vital relationships that can better the lives of all their people. Mexican President Vicente Fox treated Bush and Canadian Prime Minister Stephen Harper to an hour-long tour of the ancient Mayan ruins at Chichen Itza before they began two days of talks amid spring breakers in this Caribbean resort city. "This is a good start to a very important series of discussions," Bush said, standing alongside the other two with the massive pyramid called "El...