My company runs Exchange 2013 and all of my end users are on Outlook 2013 as well. (Obviously a premise based install) We are small office of 8 people. The president of the company wants to have 1 integrated calendar so he can see everyone's schedule, as well as using it for scheduling company event, meetings, etc. The two solutions I've given him are showing "Shared Calendars" so he can see everyone's individual calendars on any given day, week, month or setting up a public calendar for general company functions and then balancing that against his own individual calendar using the appointment scheduler when setting up individual appointments.
Up to now, the "public" calendar was hosted in SharePoint, but I've discouraged that use since the sharepoint calender doesn't send out meeting invites, reminders ect, in favor individuals people managing their own individual calendars and then scheduling things use the appointment scheduler in when creating a new event, and using conflict resolution.
I'm not aware of any other options to do a single integrated calendar... anyone have any thoughts or ideas.