Okay, I have to admit my ignorance concerning route/highway 15N. To the best of my knowledge, I can't remember ever using it. It sounds like an interstate in California(?)
But 219 is my chosen route, and I've used it quite a few times even for trips that weren't to Virginia. It used to be poorly maintained, but they have improved 219 every year now for the last 7 or 8 years. I've noticed widening of the highway in many parts, repaving in many parts, and wholesale re-routing and improving of the 219. You probably already know that the highway system is such that one digit and two digit highways (i.e.: Interstate 76,etc) are considered major routes, whereas three digit routes are secondary and/or go around cities. So, yes, 219 is secondary but it's getting better every year.
In just a moment, I'm going to email you the Mapquest route that I take to VA. If you can't open the link I send, just let me know.
Hope that helps and doesn't add to the confusion.