I'm a longtime AutoCAD (and the Mac clone DraftSight) user and while I like the Eagle CLI and the ability to do things with precision, the CAD aspect of Eagle lacks a lot compared to these types of programs. While Eagle doesn't need to be a general purpose 2D CAD program it could pick up some useful tips from them. One suggestion is object snapping -- snapping the cursor to endpoints, midpoints, circle centers and quadrants, etc. Often it's automatic. The aforementioned CAD programs also let you explicitly specify object snapping. Whenever the program is waiting for you to specify a point by clicking you can type .end, .mid, .cen, etc. to automatically snap to a nearby endpoint, midpoint, center, etc.
Another useful feature is an array command, which lets you quickly layout objects in a rectangular or polar array.
thanks,
--steve