Other than monitoring all of the services associated with AD has anyone setup monitoring on some AD metrics via WMI that might indicate the overall health of AD. My biggest concern is being able to monitor if replication has failed.
You might want to create one or more Windows Script Monitor(s) to monitor one or more parameters in the MSAD_ReplNeighbor WMI class.
msdn.microsoft.com/.../ms677408.aspx
This class belong to the \\root\MicrosoftActiveDirectory namespace so the Windows Performance Counter will not work as its connects by default to the \\root\CIMV2 namespace.
More WMI classes for Active Directory: technet.microsoft.com/.../cc739941.aspx
Let us know if this helps.