If you come to Sapa you do have to do some excursions. There are three possibilities. You can do the excursions on a four wheeled vehicle, on a rented motorbike and on foot.
One of the shortest trekking is the Ham Rong mountain. In a two-three hour hike you can get to the top of this 2,000 yards (1750m) high mountain. From there you have an excellent view of the Sapa valley.
If you want to do a longer trekking, visit the Tavan. You have to take a jeep to get to Laochai, and from there in a 8 miles (12km) trek, you will get to Tavan. Where you can see many local people dressed in their traditional clothes.