Every once in a while, you need your rail to look like a roller coaster, or at the very least it should simply follow the slope of a roof.

Revit 2017 has significantly enhanced the railing hosts. Now when you host your rail to the top of a wall, or a sloped roof, the rail will follow that slope, even if you only drew it with a single line in the sketch. This means faster and more accurate modeling and that means less wasted time.