If you are going to use the Snap to Contour, you might want to adjust…
Vectorworks Tip 338 – Site Model Settings – Graphic Attributes
In Vectorworks 2016 there is now a faster way to set the graphic attributes on your site models so that it uses the class settings for the line weights, colours, and line styles of the class. This will allow you to usual classes to change the graphic style of your site models after you have created them.