The document summarizes research that assessed the hierarchical structure of online channel use by American travelers for trip planning. The study identified four groups of online trip planners based on the number of channels used: 1) Core Travel Search, 2) Enhanced Travel Search, 3) Travel Focused Search, and 4) Comprehensive Search. It found significant differences between the groups in demographics, information searching behaviors, online purchasing behaviors, and spending. The results indicate there is a progression of sophistication in online travel planning as travelers incorporate more channels into their activities.