When you break-down props and evars by other props and evars you need to know/remember what the applicable/allowed evars and props are. In my experience we show users some new cool tracking we've implemented but no one remembers how to break them down by the other specific evar or prop as they just see a load of sub-menus which confuses them.
SOLUTION: Within the SiteCatalyst interface you create relationships between evars/props which would appear in a common break-downs contextual menu. This would allow the admin to aggregate the most common break down activity within one bucket. I believe this would be a big usability improvement for the majority of SiteCatalyst users.