It would be really cool for us to be able to group calendars. Here's an example of how we're managing social media and our blog with calendars:
Every time we want to see all of these calendars at once, we have to individually click the check next to each one. It would be great if you could check all of the calendars and then click "Group Calendars" or something. Then, you could just check one box to see them all! You could also expand the group so that you could check each calendar individually, if you wanted to.
How I'm envisioning it would look something like this:
I can think of a lot of other use cases for this, like grouping calendars by team!