Here's the thing about the Walnut Canyon Rim Trail...I'm not actually sure if I was on the Walnut Canyon Rim Trail. None of the roads, parking lots, trailheads, or trails were well marked and none of the names matched up with what I saw when I read about the trail. Further complicating things is the similarly-named Walnut Canyon National Park/monument/forest/whatever it specifically is. One of those trails is supposed to be about 12 miles, the other is about .3 miles, and the internet doesn't do a good job of distinguishing between the two.
Until I can confirm where I was, what the trail actually does, and how to get there, I don't want to spread misinformation. I assume I was on the Walnut Canyon Rim Trail, but I'll have to revisit to confirm.
Here are the photos from wherever I was in the Flagstaff area - Photos