Today I did something I'd never done before on my own.  My Aveo now has new plugs and wires, thanks to yours truly.  It was easier than I thought:  the hardest part was getting the decorative plastic manifold cover off (a couple of the screws were rusted in).  The car had not been running as smooth as it could for a little while, and this seems to have finally fixed it.  One of the old plugs was covered in engine oil (the rest were all clean), so I'm pretty sure it was the culprit.  I had to buy a gap kit and a deep socket, but that's still cheaper than paying someone else to do it, and it was good experience, too.