It would be good if:
you could create multiple reference Levels that could act as stories in section, where you could set the desired elevation and have it populate a dashed line in 3D generated views. Creating Stories is a good work around, however I would much prefer to keep the model simple with only a few stories. Controlling these lines could be done similar to grids in the section settings where it is a simple tick-box of which lines to display. this would be very helpful for quickly establishing existing & proposed ridge lines, floor set-downs etc.