Are you familiar with filtering options in the Long Form > Object Tree?
This menu will filter the list of Objects dependent on the criteria:
Off > no filter applies; all selected Objects are shown.
With Bookings > only shows Objects from the selection that have Bookings in the selected time range.
Without Bookings > Only Shows Objects from the selection that do not have Bookings in the selected time range.
Prel. Due to Object Permissions > If Object Permissions are enabled, the list will only show Objects that have Bookings in a Preliminary Status due to Object Permissions.