Dear "line-weight"- Good question. This is how I would use the layers. Say I am modeling a table. I would have the top on one layer, the legs on another. I would then group those layers into one group called table. I then group all of the groups that make up the set into one master group. I can then duplicate this and move each one, keeping that individual heirarchy in each group that is the entire set. At least that is the work flow I am used to. I have been using classes to establish a "line weight" for all my dimension lines, for example. One for construction lines. One for sections, etc. Not much more. But you are saying, I should be using classes like I would layers? The elements of the table, if assigned the same class will be grouped as the table? No matter what layer they reside on?
Thanks again for your insight
P