Unless you have good reason (like it not being available) it is almost always valuable to include the dot com whenever it is available either as the base or a redirect.
In addition to the fact that many people think primarily dot com and may not remember your extension, another reason is that many people just type in the primary part of a domain in the bar and hit "control enter" to go there because it automatically enters the
http://www and the .com for you saving a lot of time. Even if they then change the extension and come on to your site they will go elsewhere first.