The Rotate command in Revit could use some improvement. Here's some suggestions:
The center of rotating is quite often wrong. It seems to assume something like the centroid or middle of the object, not the insertion point.
I'd like to see is some quicker way to place the center of rotation. You shouldn't have to click a button in the ribbon to do that. Ideally you could get revit to automatically have you set the center of the rotate.
The fact that spacebar rotates a single element is nice, but it only works on one single item at once. It should work on a group of items....say you want to rotate 50 lighting fixtures 90 degrees in place at once, it should do that. This spacebar rotation should be available in both clockwise and counterclockwise and it should be able to assume nearby angles like tabbing during placement does.
One more addition I'd like to see in rotate would be a "Rotate in plane" option, which would allow you to say take a pipe, draw it in plan view and then rotate it to be vertical easily. You shouldn't have to be jumping to sections all the time to work vertically.