SketchUp can be a pretty helpful tool to have in a project manager's bag of tricks. It's the simplest 3D graphics program that I've seen for its versatility, and worth a try for anyone who likes to think visually from time to time.
The basic program is a free download
, and the 'Pro' version is about $400 and change. The added functionality of the full version is a little esoteric in the context of how I use it. Among other things, it allows the user to import/export files with CAD and other 3D applications.