This is a rather popular loop among ultra-runners in the area, so I wanted to post my slow time with the hope of seeing what some faster runners can do.
The loop starts at the Elena Gallegos trailhead in the Sandia Foothills, then heads north along Trail 365 to the Sandia Tramway station. From there, a small trail links up to the iconic La Luz Trail. This trail goes to the crest or, when doing the Watermelon Loop, follows a path to the Ski Lodge/Tram station. The South Crest trail is picked up at the ski area and followed to the top of the Pino Trail. The Pino Trail is then followed back to the Elena Gallegos parking lot. This clockwise direction is the standard direction.
The route is right at 21 miles, with ~4700' of vert.
I'm making an unacclimated attempt at the Watermelon Loop tomorrow. I heard there's construction around the tram station (thank you Christopher!) so I'll be double-checking everything there. I'm trying to get the Garmin website to work tonight (was very finicky and now it doesn't come up at all), but my new Mini should send the tracking points here once I start: https://share.garmin.com/MarcyBeard