Everything that has been described has its drawbacks. It is a matter of individual tastes. When sitting here at the stick house, I'll use Google Maps, or Bing.com/maps, and sometimes I'll fire up the PC laptop and us MS S&T. They all pretty much give the same information. The nice thing is if yo don't like what you see you can drag the "line" route to another point and it will re-calculate. MS S&T has a POI called "low clearances" that you an load, then plan your route. It will show you with yellow markers the low clearances on the route and you can see how to avoid them. I do not take the low clearance POI as a fully faithful means of determining low clearances. I go to the AITA web site (search on AITA low clearance) and look at the roads through the states I'm traveling for low clearances.
I don't think that there is a "one stop shop" mapping program. It's whatever you are comfortable with. I also like the Google and Bing mapping programs because I can plug "rv park" into their search line and it will populate the map with rv parks. I can then slide the map in any direction and the rv parks will re-populate. Unfortunately I still have to do so research to make sure it is a suitable RV park.
Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2008 Winnebago Destination 39W
It is what it is, and then it is what you make of it.