Route tips

Hello.  We're planning our first long distance road trip with our travel trailer.  First stop is Niagara Falls.  Any tips on best route from the Myrtle Beach area?  All of the route planners I'm using sends us through WV to avoid the Arlington... traffic.  Does anyone know if there's another, better route?  Also, what's your favorite rv gps?  I'm an apple map/siri user, but I'm checking out RV Life.  Any pointers/suggestions would be greatly appreciated.