What key elements must any waiting-line model include?

The chosen answer encompasses crucial components that directly impact the functioning of any waiting-line model. Understanding the arrival rate of guests provides insights into how frequently customers come into the system, while knowing the service duration is essential for assessing how quickly those guests can be attended to. Together, these elements allow managers to model and predict queue behavior, optimize staff allocation, and enhance overall efficiency in service delivery.

While the other options provide valuable insights into customer experience and satisfaction, they do not directly constitute the foundational structure of a waiting-line model. The experience of customers waiting in line focuses more on the subjective aspect of the wait rather than the quantitative elements that define the queue's operational characteristics. Similarly, overall satisfaction after service is an outcome of the waiting and service experience but is not a fundamental element of the model itself. Lastly, the types of services offered can influence guest behavior in queues; however, they are not essential components for the basic framework of a waiting-line model. Thus, the core elements necessary for analyzing and managing queues are primarily the arrival rates and service times, making the first choice the most relevant.