For reference, I just did the second tune on my second 2000 Astro. The plugs were due. The cap and rotor were overdue. It got wires at the same time. It's about a two-hour job including removal of the dog house and I/P parts (trim, CD player, etc. ) The plugs are relatively easy to access through the wheel openings if you carefully remove the push-pin fasteners for the splash aprons. A long-ish extension (some of them needed 18-24" to make it comfortable) , universal, and patience will get you there.
#6 had some deposits and all the gaps were over 0.080" so it was time.
