Many of the thousands of students heading for spring break this month will be packing their passports. According to Mediamark Research Inc., the most popular destination for students traveling abroad is Western Europe – 14 percent of all 18-to-24-year-old full-time students have been there. Thirty-three percent of full-time college students 18 to 24 have a valid U.S. passport, and 31 percent have made at least one trip outside the country.