You sure your '99 suburban has a cap, and rotor? Better check again.
As far as plugs go, don't get fancy, nor cut corners. Stay with the
stock AC Platinum plugs.
There will be nothing gained going with Bosch +4's, Splitfires, etc.
I bought a set of new AC's not too long ago for my '97 Tahoe. They were
$58 for 8.
Take care when removing the plug wires. Give the Boots a little twist
first before yanking them to help prevent damaging them. Also, don't
rely on the gap being properly set from the factory on the new plugs.
Check all with a good set of shims, and adjust accordingly. Mark