There are now available RV focused GPS units. Three that I have seem are RandMcNally, Magellan and Garmin.
I haven't tested the Garmin, but I like the Rand presentation of Campgrounds and RV services like Dump Stations better than the Magellan.
My older Garmin is a wonderful piece of electronics - but finding a campground is a pain. It does list commercial campgrounds under the lodging section, but the state parks, COE campgrounds and USFS campgrounds we love are near impossible to find.
Every GPS has its good points and its bad points. Information on things like campgrounds is only as good as the source the GPS company buys the data from.
Most of the 'errors' people see are the result of how the various states present their highway data.
What is important is that you be comfortable with the interface - how you use it. That means that hopefully you can test the various units which friends before making your decision.
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT