I handle large rhino files all the time. Imported CAD assemblies combined with modeled geometry in different versions. Many layers and revisions. Files above 1.5 GB is the norm.
Sometimes when looking to clean up a file, and discard things that are large and might not be neccessary, it would be good to see what in the files that takes up what space. Much like when hunting for space on the harddrive it helps to look at folders sizes and sort by size, and then drill down from there.
Would it be possible, perhaps via scripting to report how much space the geometry on the respective layers take up? So a space used per layer list so to speak.