For lack of time, I didn't read any of the previous responses. I will say we've taken our 42' motor home up to alaska 3 times (2008, 2014 and 2016). the roads have gotten better each time. in 2016, only about 40 miles of unpaved roads. the biggest thing to remember is to drive according to the condition of the road! friends that drive too fast have had issues, friends that drive slowly have enjoyed the trip immensely. my suggestion would be to take the Alcan one way and the cassiar the other way. there's too much beauty on both to avoid either. depending of what interests you have (fishing, sightseeing, tours, history, etc) should dictate your route. don't be afraid of the roads, just respect them. feel free to contact me if you want more info. alaska and the yukon are places just begging to be explored!
we have some photos at facebook.com/stoppingtheshutter and also at instagram.com/ronniesue. hope these will make you want to go!!!