As with Text add:
1 - make polylines Visible in 3D
2 - make it possible to add Elevation to polylines

If possible:
3a - add Height or Thickness to polylines, so that they appear as a real 3D-object (ideal for electrical wiring, and ducts for water and air)
3b - Add round polylines (in cross-section) to make objects in 3D appear more realistic

4 - Add X,Y coordinates for exact positioning (preferably also for Text)
5 - Make it possible to Group polylines and text
(In short, make it possible to treat polylines and text as "furniture" )

Hans