Marcus began his career as a writer with the Matador Travel Network, writing travel articles both from personal experience and internet research. He has since published hundreds of city guides for Kayak, detailing transportation methods, tourist attractions, restaurants, and accommodations. He has also written long summaries of the policies and destinations of major airlines, including Spirit Air and Virgin America. He has personally traveled to dozens of countries and hundreds of cities. He is fluent in Spanish, adding to his abilities to research locations for his work.