I have the GpsMap 76C and I am satified with it, but have yet to use it on any long distance tour. It is classified as a Marine GPS but will work well on a bike.

I would consider the Quest 2 but it's rechargable battery pack does not make it a good canidate for touring. But it's shape seems to make it a better fit for the handle bars. Plus it has voice prompts, but you would have to mount a
speaker