New for Revit MEP 2012 is the ability to control graphic overrides directly from within the system properties pallette. No more having to make filters for every view or apply View Templates to views to display systems the way you want.
The only catch to this is, unlike Filters that can override Pattern and Line Graphics, this new functionality only allows for Line Graphics to be overriden.
You can now also in Revit MEP 2012, give duct and pipe systems an actual rendering material for visualization purposes, not just a physical material for calculating flow, friction, etc.
The only hangup with this approach is that now everything on that piping system for instance, such as accessories like valves, meters and backflow preventers get the same material. It may not be realistic but it sure does look pretty!.
The traditional approach for Duct and Pipe Rendering materials in Revit has been through the Object Styles Dialogue, but even worse with that approach is that now all your pipe systems such as Sanitary, Domestic Water and Storm which could range from PVC, Copper and Ductile Iron respectively, are now all made rendered with the same material, If you are only showing one pipe type per rendering, then you'll be ok with this approach.
The most painful and tedious method of all, which would be very laborious in a large project, but would actually deliver the most satisfying results, would be to use the paint tool on all that Piping and Ductwork. Better be banking on that presentation and Good luck!