We hiked the Marshal Gulch/Aspen Trail on a week day in mid-May 2018 and it was a gorgeous escape from life in Tucson. We ran into only a handful of hikers once we left the parking lot. (There are signs re daily fees of $5.00 for parking or no charge with the Senior Park Pass. We did see tickets on a few windshields. There is a parking area before the trailhead and there were no signs re fees for that.) The temps were in the 70s and there was a cool breeze the whole hike. After the Aspen Fire of 2003, plenty pines and Aspens are making a comeback.

The trails are well maintained but there were numerous downed trees to climb over. The trails are largely protected by a canape of tall trees which helps with the sun. Take plenty of water and there is no cell service which I personally love but plan accordingly. Have a ball.