Laurel Hill Power Station Loop Trail 

I would not suggest this trail. The Apple Orchard Trail and some of the connector trails would be good for a gravel bike. See my video of the Apple Orchard trail on my channel.

you can do it on a gravel bike, it's tougher and you have to be careful on the hair pins but its still decently fun.

I just rode this today for the first time. I wouldn't have a 9yr old run it unlss he is comfortable passing bikers coming at him. The trail goes both ways. You can run short loops though. I use the AllTrails app, and you can see the different loops on it.

Much easier than Fountainhead. Stick to the trails that don't go into the woods since they are the easier ones.