I just switched from Eclipse to Android Studio. For what I saw since now the new IDE has a lot more features than Eclipse, and I like using the new IDE for my app developmen
There are several ways you can find the DDMS tool using android studio. Eclipse is not needed for that as the tool is a separate program that comes with the android SDK.

monitor in the terminal in Android Studio or in any command prompt. (thanks SimonVeloper)
This will open the DDMS tool and will automatically connect to connected devices.
Normally you will be able to view your logcat output through this tool and not in android studio anymore. If this doesn't work for you make sure your devices is properly connected and restart the tool.