While I have had great success navigating with the Garmin Edge 800 using per-plotted routes created with Map My Ride, I have found navigating on the ground with the device a great frustration. On previous rides I have struggled to get a sense of where I wanted to go from the small screen.
On a recent ride in Portugal, this technique came to me and I have found it very useful. I zoom out till I can see a number of place names, then choose one in the direction I want to go. I then go to Where to? And Cities in the sub menu and pick out the place name I want, generally 6 or so K away. Routing to this spot with no tolls, trunks etc. generally produces a quiet ride. On arrival I repeat the steps moving in the general direction sought for my final destination.
This has worked well for me and has taken me on some interesting back roads to some very small hamlets here in Portugal. Certainly beats the local paper maps that are usually very inaccurate in my experience.