Many thanks once again to those that responded to my original posting
(and my follow up message) with information about Network UPS Tools, other Linux-based tools like rtcwake, and commercial UPS products. We have quite a bit more evaluation and testing work to do before a power fail protection method is selected.  I hope the discussion is as beneficial to others as it is to my organization.

Along the way, one of our users pointed out that some of our CentOS 6
desktop/deskside machines actually throttle back power consumption in different ways than others.  Instead of the yellow/amber LED display in the center of the power button, they flash green and then go solid green after the power button is pushed and the system wakes up.  We have also noted that none of our CentOS 6 systems restart on their own when power is restored. This is the case whether power is lost during normal operation or when the systems are in a standby state when line power is lost.

These two conditions or states (yellow/amber vs flashing green) have us wondering exactly what standby mode these systems are in and what settings may have been selected to send them to their standby state. Is there some sort of standard that applies to the standby states and are there BIOS settings or configuration files that control the what, how, and when standby is directed?

Thanks to all and best regards.