I have had a few GPS devices in my RV for family trips and my favorite is my new TomTom XXL 540TM. It is by far the easiest and the funnest gps to use. I have a Garmin gps too but really prefer the TomTom.
You just touch the screen and follow the directions to use it. You need to update the maps with the free update you get immediately after purchasing your TomTom XXL 540TM. This will avoid it sending you down some street that has been closed etc.
It has a 5 inch wide screen and cool graphics to show your surrounding area.
There are over 1200 customer reviews. R. Pertusio says it is his favorite GPS and gives a very long detailed review.
Now some people will not like the fact that it does not have voice recognition. Personally I have never cared for voice recognition in anything because it just never works consistently for me. Even my wifes brand new Lexus with voice recognition cannot figure out if I am saying Pizza or Home.
The bottom line, if you are wanting to get a gps and not spend a big chunk of change this TomTom XXL 540TM is for you. Go read more reviews here.