I began by trying out All In One Calendar from http://www.theseedstudio.com
but I could not get it to work with the multisite I am working with. So I am now trying Events Manager.
Installed and began looking at the settings. There are A LOT to choose from. It seems the logical way would be to create tabs (accordian style) that can be opened and closed depending on the needs at hand.
Since I am located in Norway I switched the location and looked for a way to change the time and date format (backend and frontend). Since it is easy to change the country it would be natural to right below change the time and date format through a drop down box or similar.
The default frontend or events page comes out as very stal/steril looking calendar. What about adding a custom style layout for the look of the calendar? It can have its own tab called calendar design layout. Selecting various colors to use etc.
That is my first impression.