There has always been a way of adding areas of polylines up in AutoCAD as far back as I can remember but it was always hard to remember with lots of areas which were included.
Not any more. AutoCAD has subtly added a new feature (I like these sort of improvements) where it now highlights the areas added.
Area –> A (for add) –> O (for Object), gets you to the add mode for areas and this is what you get, a nice green highlight when the object is selected. Ah, that was satisfying!