Tara,
Great question. There are a lot of variables but I can share ideas that have worked for me. I have classes that are from 20-25 in a session at a time. In a hospital, the group can meet in the waiting room or lobby, or even the parking lot. By yourself, you can take teams of 5-6 to the area to be observed while the waiting students have a "waiting" assignment (discussion, writing questions to be asked, etc.). If there are several areas that are to be visited, the class can be divided, with each group visiting different areas, rotating so that each group sees all areas. If you can get a fellow instructor, or a graduate, or a senior student to assist, this helps supervise and manage a larger class.
Even with a smaller group of 5-6, this group can be divided into an even smaller collection of 1-2 while observing a procedure or special area of attention, rotating among the remainder of their waiting group until all have participated.
I tell my students when they are walking in the hall to "stay to the right", following behind me in a single file in order to minimize blocking the corridor. If we stop to chat, I instruct them to remain "clustered" so as to occupy the smallest space and by no means blocking any doorways, corridors, or areas where hospital work flow could be interrupted. I ask them to observe what is to me obvious things, but to them, anything that looks unusual or unfamiliar. This provides for discussion after the visit. Also, I insist they remain virtually silent as we walk about. I want the "touring group" to be almost invisible to the working staff. The intrusion of a group of non-workers can be a bit disruptive, so I emphasize the importance and as above, insist on absolute adherence to my preliminary guidelines.
As I said, there are a lot of variables. I hope this will give some ideas how you can make these important visits memorable and successful.
Barry Westling