Those are the ones that need redundant power backups to maintain full availability. Prioritize other systems and determine which, if any, should be backed up. Any backup power system needs to be scalable so that it can easily grow as your power needs grow. Make sure it can handle at least 3 years of projected growth. Make sure that the backup system provides steady power while electric circuits are added to or taken off the system.
Generators spike and slow down during changes in power demand.
UPS systems help smooth out this power demand. If using multiple generators, make sure that they are compatible with one another. Also make sure that any generator is compatible with your UPS system. I was a control system engineer for SCE in my past life and now provide sales and services for computer sytems including UPS and surge protection. Please feel free to contact me should you have any questions.