"Jenkins Cache" is at the Jenkins Arboretum. It's a nice walk on paved paths all the way because they didn't want anyone stepping on the plants. It's also educational; all the plants, even the wildflowers, are labeled, so maybe I can figure out what's in my back yard by comparing the weeds to the photos I took at the arboretum. I think I have some wild violets.
"BSA100yrs" is another interesting cache. It's inside the Valley Forge boy scouts building. It's just a scout-themed box that any ordinary visitor would simply assume was part of the exhibition but I knew it was the cache as soon as I saw it.
"Please stay on the trail" is another good one. Coordinates were only provided for the trailhead. Then you have to walk on the bike path and measure 0.28 of a mile using the GPS odometer. Of course, there were inaccuracies. My GPS odometer actually read 0.29 mi when I found the cache, so it's a good thing the cache site was obvious.