I went hiking through the rice paddies in Sa Pa, Vietnam (northern mountain area). The town is swarmed with Hmong girls trying to sell handicrafts, following you throughout the city from the minute you leave your guest house. So yeah, it's full of people and tourists, parading through the rice paddies. But it is still their life, and a very unique way of living.
Advice: colder up there, bring layers. I went in March. Your fancy hiking boots are of no match for these fields - super muddy and slippery.