If you've been on pins and needles over my air conditioner dilemma, feel free to relax.
The service guy finally arrived about 4 PM. I hadn't even worked up a good sweat yet.
Indeed the issue was the contactor and it was a simple fix. I was reluctant to perform the service myself, but after watching the pro do it, I won't hesitate to do it next time, which I am sure will be sooner than I want it to be.
He charged me exactly the $115 he quoted me on the phone. He didn't try to pull the old, "hey, it turns out the flux capacitor is also shot and that will be another $250."
He said that 90% of the time the problem is with ants that have gotten into the contactor. They leave, as it turns out, some sort of slime (ant poo?) that insulates the plates and prevents them from completing the circuit.
My A/C unit was humming along again by 4:20 and my house was cooled down an hour or so later.
Sleep was tremendously improved last night over the previous one.
Just another day in the life...