I most strongly urge anyone to take a couple steps in route planning.
1) Make sure you know the route YOU want to take, not the softway. The highways you want to use.
2) I advocate printing out the route from what ever planner you use, and work with your co-pilot/ partner/ DW so that he or she can help you when on the road.
3) Program the GPS the night before a trip, verify it actually follows the route you want to take. Save the trip.
4) ALWAYS use "Quickest Route" setting on the GPS, NEVER use "Shortest Distance".
5) Don't blindly follow the GPS, it if wants to send you somewhere you were not planning - pull over, stop and look at a map.
6) I recommend turning off/ muting the voice on a GPS. The distances the voice gives you for turns are too short for an RV. You will not be able to slow down, change lanes, etc. Make sure your co-pilot knows how to work the GPS, and to give you amble notice of turns, lane changes, etc. Learn if your GPS has options to customize how soon you get such warnings.