So, I think cycling is one of the best ways to visit Vietnam. The experience is very different from cycling and sitting on the bus. There is quite a bit of interaction with the locals - a lot of the kids (and some adults) excited wave/shout "Hello" as we ride by, and they burst into giggles when we respond. In one town where we waited for others to catch up, we literally stopped the traffic. I guess people there get so few visitors, we were something to gawk at.
I can't say enough about the views - they're simply breathtaking.