Search Competition Among Travel Sites sees Juice provide a fascinating insight into their pattern analyser as applied to travel queries in the US.
Lovely chart showing how head- or tail-focused a site is:
Head vs tail queries for top travel sites
The question is how much profit each site makes from its hits. I assume the head-focused sites do thanks to their focus, rather than the scattergun monetisation the long tail sites need.
If you want to know how their neat bubble charts are done, they kindly explain in a later article.