Most Gn15 layouts are patterned after small gauge railways located within the grounds of an industry such as a gravel pit or other mining operations, etc. But, an amusement park attraction would be another good prototype to model.
My favorite Gn15 layout was based on an actual 15" gauge line some railroad buff built to transport items from his driveway in front of his house out to a shed in his backyard.
He laid rails and built a small gondola pushed by hand. One stop was at his back door for groceries and the next and final stop was the shed out back. Then he built a model railroad of this prototype road in his basement in Gn15!!! 
Jim
