It would be helpful if there was a priority flag on the tasks. I primarily use the Calendar view, and I'd like to be able to see the priority of the items on the task header without having to open the task to find out. I do think this would be helpful in the other views as well, I just don't use those as much.
I'd also like to choose how the items are sorted in the Calender view. For instance, I'd like to be able to sort them by Priority, having the most urgent items display at the top. However, I also think it would be helpful to have a "custom" sort... for instance, there are some days that I want to be able to sort my tasks in order of how they need to be completed. For instance, if I have 3 urgent tasks, I'd like to be able to place them in the order I'm going to work on them, so that I can just work my way down the list.