While Hoi An old town itself is beautiful and charming and can easily keep you occupied for a few days - if you do not venture into the surrounding countryside then you would have missed out on another side of Hoi An's charm. The countryside with picturesque small houses and green rice fields is a joy to explore. The best way to get around is by bicycle - which really lets you get close and down and dirty.
Rice fields cover much of the country side - and many of the bunds around the rice fields have been sealed with concrete making them perfect for motor bikes which are the preferred mode of transport for the locals - but bicycles also benefit tremendously form this informal network of small roads.
The roads can be a bit difficult to navigate and you can easily get lost. It is good to bring along a handphone with GPS to find your way back.