Scott, with regard to the idea of highlighting a section of a profile (great idea!) perhaps you could add something like NGS Topo does. As you select any point on a profile, a horizontal line appears that allows you to read the elevation scale, and a vertical line appears so you can read the distance from the origin. Also, when you click this point, a marker dot appears on the profile, and the corresponding point on the map is also marked (with a small dot) and horizontal / vertical lines appear. The marker dots stay in position until you click another spot on the profile. This is a bit different than the way TF works, but I find the NGS Topo! features very handy! Especially the markers that stay in place, and the ability to see the whole trail as you move the markers.
Larry