The ease with which you can set up different types or rules for your business; it makes managing multiple locations easy! I wish there was more control over who could sign out when they were finished visiting one area (this would be helpful if we are using this as an employee time tracker).
We have been able use cap sure at our local office center building - allowing employees from other offices across town to visit without having someone manning reception during normal working hours. This has saved us money by not needing additional staff members just so people don't wander around unsupervised while waiting outside another branch's lobby/office space.