Hi Scott,
As you stated, VectorWorks has a default lighting scheme so the addition of lighting devices is not necessary, but once a light is placed that default lighting scheme is hidden and only the lighting devices on that layer are used (regardless of if they are turned on or off). Also, OpenGL only renders up to eight lights in a drawing; additional lights have no effect.
This could be the cause of your dark lighting. If you have more the 8 lights in the drawing Open GL will only utilize the first 8.