My first suggestion would be participant observation, this way we can see exactly what the guests are experiencing as they are experiencing it. Second could be experience surveys. This would allow us to survey guest and employees to find out what they liked/disliked and suggest any ideas to better serve them. Third could be focus groups. This would allow to get provoke more thoughts and genuine feelings from guests/employees because the group would be lead by a trained moderator. Another suggestion would be a correlational study to determine of the tension among coworkers is the leading cause for guest complaints about employee attitudes.