[lsc]

The PDUs that support 'staggered power-on' are 'off the shelf' - if that is not an option (really, we're talking maybe $500 for each 20a circuit, retail) the next thing I'd do is set 'power on after power fail' to off, then have some remotely accessible way to trip the power button. (I'm working on a solution to that particular problem, but that's not 'off the shelf' - yeah, everything is on PDUs I can trip remotely, but there are reasons why it is much better to ungracefully reboot with the 'reset' jumper than to ungracefully reboot via cutting off the power.)

from there it would be easy enough to have an automated process turn on servers one at a time.