A time to travel across the globe, usually in summer.
Passports create the feeling of travel, usually by plane, and they enhance the theme by putting the idea of travel and planning in people's mind. This all creates the idea of a world traveler.
Old fashioned trunks/suitcases
Old fashioned trunks imply travel as a more glamorous and vintage activity rather than just a way to get from one place to another. The suitcases can give a sense of urgency to pack and go somewhere. Both enhance the theme by making people want to pack up and travel the world.
Globes create an idea of the big world being small enough to travel to any place in the world. The globe enhances the idea of world travel by showing the world in a small appealing map. Globes make people think of the world and thus, of traveling all over it.