Do the navigation GPS units come with handlebar mounts so that you can see the map while riding?
You don't need a map to use a GPS. I've traveled hundreds of miles with GPS units that didn't have color maps. I have the Garmin CX unit with built in map but rarely use it. I make all my routes at home, upload them to my GPS, then turn on the arrow feature to point me in the right direction. Simple.
The picture below is all I need and nothing more. However, should you get lost or the route doesn't work well, a built in map is nice to have in case. This is rarely the case and I still use ONLY the direction screne pictured below.