From the January issue: Think of Florida as the pop star of vacation destinations: both popular and cheap. While the market there is in a profound rut, it remains the most popular second-home market among American buyers, and the weak dollar is attracting Europeans, Canadians and South Americans. To understand how the Sunshine State developed as the nation’s No. 1 vacation home spot for Americans, just glance at a map of the U.S. interstate system. Florida’s main west coast highway, I-75, runs straight into the heart of the Midwest; its east coast counterpart, I-95, runs directly north to Washington, D.C., Philadelphia, New York and New England. Before air travel became the transportation mode of choice, families drove or took the train to Florida.