-When creating a pipe run from a feature line, have the option for the pipe run to use the elevations from the feature line for the pipe inverts... Add a drop across manhole setting (i.e. 0.2').
-Have the ability to dynamically link the pipe run to the feature line. The pipe run would update horizontally and vertically when the feature line is manipulated and edited.
-Have the option for Civil 3D to automatically create an Alignment and Profile when creating a pipe run from a feature line.