Labor Day Weekend. September 1-3. One of the nation’s most popular international music and arts festivals, held at the Seattle Center. It draws more than 500,000 visitors each year. www.bumbershoot.orgNorthwest Folklife Festival Memorial Day weekend at the Seattle Center. One of the largest free folk festivals in the country attracts more than 250,000 visitors and a wide diversity of performers, participatory dances, workshops, crafts, food and more. A colorful, dynamic scene.