Original Poster's Results
Original poster here.
I ordered a Sony single DIN with dual USB and Bluetooth from Crutchfield. They sent me the installation instructions as part of my order confirmation so I was able to get familiar with them before the unit even arrived. Included with the unit, free of charge was everything else I needed for the install, including the dual to single DIN adaptor, wiring harness, and 12V to 5V convertor for the woofers. The only other thing I purchased were some wire connectors that screw instead of crimp.
True to other's posts, the instructions clearly explained how to take everything apart to get to the existing radio. The wiring diagram was very clear as well and it was nice to wire everything at my kitchen table instead of leaning into a dashboard. The only issues I ran into were (a) trying to figure out which of the 2 options for fastening the radio to the dash adaptor I should use for the best fit/look and (b) the RCA connectors for the woofers collided with a steel support bar behind the radio so I had to by a couple right angle adaptors from Radio Shack. Crutchfield's tech support helped me to resolve those quickly.
Otherwise, it all went together without any problems, which I consider a success for someone whose last install was an FM convertor in about 1978.
So, for about $30 more than the quoted price to install an auxiliary jack, and a little work, I have a new radio with a lot more features.
I would definitely recommend Crutchfield and a self-install if you're even slightly handy. They make it pretty easy.