Easy and safe, no road crossings and large unpaved route.
The trail follows the river and travels through the forest on an unpaved road for 18 mi/30 km. From Auronzo to Misurina it's all uphill, with a tough last 3 mi/ 5 km part, which reaches 15% slope grade. The reverse direction is much easier and more suited for families.
All along the trails there are picnic tables, but water can be found only in Auronzo or Misurina, same for food.