In full-fledged 3D programs like 3D Studio Max and Maya, you can see several views at once: top, left, front and perspective. You can do the same thing in After Effects!
After adding some 3D layers to your Comp, choose View>New View.
A new tab will appear in the Comp window. Drag the tab away from the Comp window until it becomes a second, floating Comp window.
Set the camera view in this window to Top, and arrange two comp views any way you like.
Go to View>New View two more times and create two more floating Comp windows with camera views Left and Front.
Finally, choose Window>Workspace>Save Workspace. When AE prompts you for a name , type Four 3D Views. From now on, any time you want to bring up a Maya-like interface, you can choose Window>Workspace>Four 3D Views.