[Jonestead]

I use a Garmin DEZL as a primary unit  for work (I drive an oversize tractor trailer) and play (car or Newell)
and Google maps occasionally (mostly for traffic)

Google can get you in really bad places really quickly (ask me how I know...lol)

Garmin (dezl is the trucker version, rv units have same mapping) and as you probably know, it allows your specific vehicle data to be configured (width, height, weight, lenghth) and should keep you off roads you shouldn'tbe on in the coach...should is kinda my disclaimer because nothing is perfect, but it's really quite good.

There are alot of little extras in garmin that I really like, like it's has real-time and posted speed that's accurate to within feet, it warns of road conditions (curves) and school zones, lots more. As Richard so eloquently stated. Mine has a magnetized mount, so I have one in Newell, one in truck and one in car, so I just pull headunit off the mount and pop it in whatever I'm driving. Very handy 

They are pricey but from my experience they are more than worth it. It also has regular car mode so it'll double duty in the car when you might not need the special routing 

I can also get Garmin DEZL for really good deal so if anyone is interested, let know savings more than cover shipping