Who has an interest in saying that the influence of companions is always the top category for choosing a trip? It's often an incentive from agencies selling group packages, or from those who want to avoid planning themselves, not a universal rule. For a solo traveler, for example, this "influence" is nonexistent; my decision for the IT-Messe in Munich last year depended on my interests, not friends. The selection process is personal, and the motive of the trip often takes precedence over the identity of companions.