public void GetInfo_FamilyInstance(FamilyInstance familyInstance)
{
    string message = "FamilyInstance : ";
    // Get FamilyInstance AnalyticalModel type
    if (null != familyInstance.GetAnalyticalModel())
    {
        message += "\nFamilyInstance AnalyticalModel is : " + familyInstance.GetAnalyticalModel();
    }

    // Get FamilyInstance host name
    if (familyInstance.Host != null)
    {
        message += "\nFamilyInstance host name is : " + familyInstance.Host.Name;
    }

    foreach (ElementId materialId in familyInstance.GetMaterialIds(false))
    {
        Material material = familyInstance.Document.GetElement(materialId) as Material;
        message += "\nFamilyInstance e material : " + material.Name;
    }
    // Get FamilyInstance room name
    if (familyInstance.Room != null)
    {
        message += "\nFamilyInstance room name is : " + familyInstance.Room.Name;
    }

    // Get FamilyInstance structural type
    message += "\nFamilyInstance structural type is : " + familyInstance.StructuralType;

    // Get FamilyInstance structural usage
    message += "\nFamilyInstance structural usage is : " + familyInstance.StructuralUsage;

    TaskDialog.Show("Revit",message);
}

Public Sub GetInfo_FamilyInstance(familyInstance As FamilyInstance)
    Dim message As String = "FamilyInstance : "
    ' Get FamilyInstance AnalyticalModel type
    If familyInstance.GetAnalyticalModel() IsNot Nothing Then
        message += vbLf & "FamilyInstance AnalyticalModel is : " & familyInstance.GetAnalyticalModel().ToString()
    End If

    ' Get FamilyInstance host name
    If familyInstance.Host IsNot Nothing Then
        message += vbLf & "FamilyInstance host name is : " & Convert.ToString(familyInstance.Host.Name)
    End If

    For Each materialId As ElementId In familyInstance.GetMaterialIds(False)
        Dim material As Material = TryCast(familyInstance.Document.GetElement(materialId), Material)
        message += vbLf & "FamilyInstance e material : " + material.Name
    Next
    ' Get FamilyInstance room name
    If familyInstance.Room IsNot Nothing Then
        message += vbLf & "FamilyInstance room name is : " & Convert.ToString(familyInstance.Room.Name)
    End If

    ' Get FamilyInstance structural type
    message += vbLf & "FamilyInstance structural type is : " & Convert.ToString(familyInstance.StructuralType)

    ' Get FamilyInstance structural usage
    message += vbLf & "FamilyInstance structural usage is : " & Convert.ToString(familyInstance.StructuralUsage)

    TaskDialog.Show("Revit", message)
End Sub