I think that a dedicated locations layer in C2 would save time and be altogether an outstanding addition to the editor.
Before I explain in more depth, here is an example, from Starcraft Broodwar's Campaign Editor, of what I mean:
If you look under the "window" tab, you will see that the layer that is active is the "Location Layer." If this layer wasn't active, the locations would be invisible. That's because the locations, which are just semi-transparent blue boxes, are nothing but location markers. They are the same as a transparent box/rectangle is in C2, except they aren't physical entities, so they needn't be akin to a pure alpha channel, but could instead be 4 (x,y) markers signifying its location.
Anyways, I'm sure many of you are thinking something like "why add this, you can already do it with transparent objects?" While this is true, activating a locations layer is a really pleasurable, smooth experience. Once within that 'mode', your cursor would have 2 functions: to create locations that aren't yet made, and to select/move/resize locations that are already there. Likewise, simply double clicking a location could allow you to change it's name, or apply a z-value (or set of z-values) to it. Then, when you switch out of the locations layer, they disappear.
I know that this might seem superfluous at first, but I just really think it would add an awesome new way to identify locations (as well as placeholders, since locations could act as objects and follow things, or do whatever else) into C2. For anyone that has used Starcraft Broodwars Campaign Editor, you know how fluid the locations system was, and how lost the editor would have been without it. While C2 is far from lost without it, I believe that it would add another candle on top of the cake.