IMHO, I'd stick with Delco's, but I have seen a fair amount of the Delco platinums lose their platinum puck on the ground strap (there could have been a design change since then...I keep in mind that these plugs have probably been in cars for at least 5 years, so manufacturing processes get better). I haven't seen any Delco irridiums that had been run for any length of time, so I can not comment on those. Over 4 years, I have seen Bosch single platinum plugs rendomly break the creamic and leave about a 1/3" chunk in the cylinder, which does wonders to the combustion chamber (have seen 2 in person, heard of 3 other occurrences). Bosch single platinums do not seem to run well in a GM, broken or not. Bosch plugs do seem to run well in a variety of imports though. NipponDenso plugs are really a good performing plug, again IMHO. Their longevity seems pretty good as far as their platinum and irridium plugs go. Side note--Accel header plugs are an overpriced Denso plug in a yellow box...but maybe they do chop a quarter inch off the length. Then you have Champion and Autolite. Both seem to have a fairly solid platinum plug at a fair price.
As far as the idle reset procedure goes, what years does this pertain to? On the earlier GMs, they say that driving over a certain speed or holding the engine above a certain RPM in park will reset the IAC valve. Those were also the years that jumpering the ALDL would extend the pintle, then you wait 30 seconds for the IAC to fully extend, unplug it, set the minimum air rate screw, then plug it in and hope the IAC counts aren't pegged high or low.