"Stairmaster Sanitas" is a great place to get a very real workout in. We are in decent shape and climbed up Sanitas and went back around the valley loop trail within 2.5 hours. I would categorize this as "moderate to hard" given a few of the rocks you have to scramble over and how steep it is. While you can carry a child on a backpack up an down, it's not the greatest one to choose for that since you might have to shuffle a bit over rocks, etc.