For many this is common knowledge but, in case it isn't...
If you have the Abode Design Standard suite you can use Acrobat and Acrobat Distiller to pre-flight your separations and ensure you don't have elements missing or included that you don't want on your films.
Before outputting to your rip:
Printer = Adobe Postscript® File
PPD = any letter sized printer
Options = Fit to page
Print this Postcript (.ps) file to your desktop and open it in Acrobat. Under Advanced>Print Production>Output preview you can turn off the process colors and leave the spots on. Check "simulate overprints" and you can scroll over sections of your stacked spot colors to see % coverage, etc.
In Acrobat you can open Distiller under Advanced>Print Production>Distiller. Drag the .ps file into Distiller and it will generate a .pdf on your desktop with each page as an output preview.
I wish that my rip had this built in as it saves a lot of film and time especially for those outputting larger films.
I'm sure many of you here can add some refinements to this. I defaulted to letter sized but perhaps you can output true size .ps and generate .pdf via distiller as well.
Hope it helps!