American Express Travel’s new Nextpedition program offers customized mystery trips for flexible young travelers. Take an online quiz regarding your hobbies, interests, and social media habits to determine your sign from ‘‘adrenalista’’ (outdoor adventurer) to ‘‘technologian’’ (high-tech). A specialist creates an itinerary based on your sign, budget, and travel history. A special smartphone arrives on your doorstep a few days before departure, providing your itinerary, Lonely Planet guidebook content, restaurant recommendations, and other travel tools. Nextpedition offers itineraries for groups and solo travelers starting at $1,000 for a minimum seven days, based on two people traveling. Available only through American Express Travel’s Cambridge office.