Another well written article, Andy.
Also, thanks for pointing out the "flat" roof tip for creating a ceiling in our sims homes :-)
One thing about building a roof that really gets under my skin is, the floor tile "sides" get exposed leaving that awful mis-matched lines around your roof in certain areas.
And too, the posts, they only look more natural with a hipped roof or on a long side of a gable. If they are placed around a porch on the front side of the gable, they do not meet the roof making it look like they are not tall enough.
Just some more building points I just wanted to share if you are into building more realistic looking houses like me.