Here is a little more to throw on the fire.  I see both sides of the lightwave layer scheme.  It's very accessible but it's also not obvious what is in their just by looking at it. 
 
I use C4D and tags can quickly add up and C4D has a ton of them.  If you limit you're scope of tags maybe this would be good otherwise you can end up with ten tags for and object quickly.
   
 |