It would be really nice to be able to setup multiple event calendars in SiteCatalyst. Essentially, it would be a way to create folders for your events while still being able to have different icon sets as well.
Also, it would be nice if you could create Annotations on charts so that you don't have to leave a report in order to add a calendar event. Currently, if you wanted to send a report to someone but needed to add a calendar event first, you would have to leave the report, add the calendar event, then go back to the report and send it. You also don't have the ability to see a note on the chart itself, which makes it harder to interpret the chart since you have to look at the bottom of an emailed report.