Did a quick loop d' loop of the ski trails at the Piedmont ski loop. It was a well maintained trail and I am pretty sure that the group I showed up with were the only people there.
There is a scenic overlook along the trail that has a wonderful view of the western part of the harbor, at night with the lights it is a gorgeous sight to see.
This would be a great trail to learn on, it is mostly flat and only has a few hills of note. There is the short loop for skate skiing and it has two hills if you do the long loop, but if you take the short loop, notably C to D, the stretch front C to D is one downhill and drops you right into the downhill stretch at the end of the outer loop, you never really get a chance to slow down and at night when you are trying to find the trail in the shades of white with a headlamp it is a bit unnerving, but during the day I bet it would be a blast.
The downside of the trail is that it is really short. I had to take the long intermediate loop ( not doing the "difficult" sections at night via headlamp). Plus three loops around the short skate loop to get to 3.6 miles.
The trails right now are in good condition, there were a few icy spots, but no rocks. The trails are not illuminated at night, alas, you have to go to Lester for that.
The trails are well marked, although there were a few spots where I had to think about where I had come from to determine where the map was telling me to go.
If you in the neighborhood check it out, the trail is right off Hutchinson rd. Which is the first left after you get heading up the hill on piedmont past the five corners mess .
I would look at a real map, my directions suck.