Workflow if then to select Approver

Assuming you have a Department object type and that you have Manager as a property in the Department Class you should be able to use indirect references for the approver like this department.manager.m-filesUser

Totally agree. We resisted initially to create a Department Object (We actually use smaller Team Object) 

When we first launched M-Files, we just used a single select value list for our Departments - huge headache - don't recommend. 

We now use a Team Object, which is related to the Employee Object. The employee object is tied to our Active Directory and updates every night. Some employees are managers - so there is a property on the Employee object that indicates this. The Employee also has a terminated date. 

The best benefit of this approach is for those situations when an employees works with more than one team. This approach handles this so documents that are restricted to Team 1 or Team 2, then can access because they're a 'member' of both

Totally agree. We resisted initially to create a Department Object (We actually use smaller Team Object) 

When we first launched M-Files, we just used a single select value list for our Departments - huge headache - don't recommend. 

We now use a Team Object, which is related to the Employee Object. The employee object is tied to our Active Directory and updates every night. Some employees are managers - so there is a property on the Employee object that indicates this. The Employee also has a terminated date. 

The best benefit of this approach is for those situations when an employees works with more than one team. This approach handles this so documents that are restricted to Team 1 or Team 2, then can access because they're a 'member' of both