I am a cabinetmaker, and not surprisingly I draw a lot of objects that incorporate moldings. Crown molding, baseboard, panel mold, frame and panel sticking, counter top thumbnail, and so on. I draw these moldings in SketchUp as extruded profiles, and they typically involve a mix of flat surfaces with hard edges and curved surfaces with softened edges. And in elevations and sections, I need to dimension things like the height of the baseboard, the height of the cabinet from top of baseboard to bottom of countertop, and the thickness of the countertop. Pretty basic stuff, but holy cow, Layout is TERRIBLE at it! The problem is getting the dimension to snap to the edge of the molding, instead of one of the serveral very nearby softened edges of the cove or bead or ogee edge of the molding. It can be darned near impossible to convince Layout to choose the right one, and it’s incredibly frustrating, when something that should be simple can take forty attempts (not exaggerating) to accomplish.
The simple fix would be for dimensions not to snap to softened edges. Doesn’t this make more sense anyway? The softened edges of faceted curves are a modeling artifact which have no relation to the real world, so why would one ever want to dimension them?