Carousel will show results from listings in Google Maps using categories. Just as in regular ranking, Google’s algorithms take into account many factors to select the places and results that are most relevant to the user. This algorithm based approach is also used to decide which businesses are in the carousel. The Google business listing is one of several sources Google uses for the photos in the carousel, and making sure high-quality images are posted to it will help improve your photo. However the image selection, like the actual ranking of businesses, is primarily decided by algorithms and so Google can’t guarantee complete control over the image. For hotel searches only advertisers and Google’s hotel finder are visible above the fold. Get the full story at Blumenthals blog Read also "The Google Knowledge Graph carousel as it relates to hotel searches"