Is there anything comparable to LMAN or Layer States from AutoCAD?  I want to save layer states (frozen or thawed, off or on, etc) so it is easier to switch between floors in a single .dwg file that may have 50 layers or so.  Also, Layer Filters is really buggy.  It only adds selected layers that are visible on the screen and is tricky about getting the filter window to pop up when you are dragging layers to a specfic filter.  Also the filters only seem to group layers but does not save the state they are in which is nice but not as useful as it could be.