Before setting out by plane, train, or automobile, globetrotters turn to a variety of sources to map out their adventures. Half of all Americans say they use some sort of travel media to plan their vacations, according to a Travel Industry Association of America (TIA) poll. Twenty-eight percent read newspaper travel sections, and 21 percent have visited a Web site or watched television travel shows. For travelers who use more than one resource, 26 percent say they find Internet sites most useful. The reason: Web sites are available 24 hours a day, can be accessed from both home and office, have the most up-to-date information, and contain large volumes of information, according to the TIA.