Is the venue an inherently noisy or otherwise distracting environment?
Does your staff have the expertise for day-to-day maintenance of the technology? Is there someone on hand to tackle small problems?
What story does the visit tell? Does it have a satisfying beginning and end? Does the visitor need to experience the elements in a particular order?
How challenging is the visit? How fun? How provocative?
How long will your content remain relevant? Can you add new content over time?