We took this trail over the course of two and a half hours, including a time to stop for lunch. There are nice views of the Etna peaks and a walk through both the lava fields as well as through the woods.
This hike would be OK for our purposes with the people that we want to take. The only thing that I didn’t like about it was that, to complete it as a loop, the second half is primarily paved and, unless we did it incorrectly, returns on a road. Here is a map of the path that we took, starting and ending at Sentiero Naturalistico Rifugio della Galvarina. Here is the page on the Parco dell’Etna website for the trail.