In Civil 3D there is no reference in "Help" anywhere to a command that is found when you select something(s) and right-click to bring up a shortcut menu. At the bottom of the pop-up menu you will see "Select Similar". The SELECTSIMILAR command, which can also be entered at the command line, will select/highlight all objects that are the same as the one(s) you have selected. I have found this to be a very easy way to select all objects of a particular type.
By the way, this same command can be found in Land Desktop 2005.