VU / PPM meters provide another level reference in a classic visual format with different ballistics. Volume Units show an average level of loudness tied to the “crest factor” while Peak Program metering will provide faster response for monitoring transients.
Mid-Side meters will help you gather information about the relations between the mono and the stereo content of a track in terms of “overall energy”, so you can choose whether to go for a more widespread stereo image or a narrower “in-your-face” kind of sound.