"he won't be staying overnight, etc"
I am not sure what you mean be etc, but I would consider spending a full day including an overnight visit. Tours are time consuming and expensive and I would recommend trying to get the most out of the experience. As mentioned, the lesson is not an audition but rather a opportunity to assess the teaching style and personality of the studio head. Try to arrange the visit so that you can also observe a student concert or rehearsal. Also consider meeting and touring the academic departments of interest. Also setup an appointment with admissions.