By default, for round robin queues (flexible or strict) your users will see the next assignee with a star as the default person to book a meeting with. This assignee is the user with the fewest meetings assigned so far based on the rules you setup
This is what your users will see:
Prioritize Velocity
You have the ability to change this setting if you want to prioritize velocity (prioritize the time that works for your guests) instead of fairness. To do that, you have to go to Workspace Settings > Round Robin Settings > uncheck this box:
Once this box is unchecked, your users will see the Availability for all assignees as a priority:
Red: No one is available
Gray: At least one person is available
White: Multiple people are available