DotNetNuke is quick to set up and get running. It is the best ASP.NET CMS that I have used.
It comes with many modules, and can be extended with numerous commercial and free 3rd party modules.
It is very easy to change to look of a DNN site by simply changing the assigned skin, and many 3rd party skins are available as well.
Warbeats.com runs on DNN, and handles quite a bit of traffic.