The option to group layers, for example; one group containing all the fixture layers. Another group containing the rigging layers.
That is a exemple from other software.
The main advantage for me is that you can Lock/Unlock or Make Selectable/Not Selectable for a whole group in one click. Also it could be nice to be able to adjust the layer colours for all layers in a group. So the feature request would not only be to have Layer groups, but also to be able to change the properties of all the layers in a group by changing the properties of a Layer group.
this could be levreged perhaps to use something like layers/classes which would help alot when importing MVR from vectorworks.