So starting at 11 PM, I started replacing three ceiling fixtures. Demolition only took 30 minutes. Installing the first fixture took the next hour and a bit more, during which time daisy_knotwise unpacked and prepped the other two fixtures. The next two fixtures took about 15 minutes each. Then we had to figure out how to install the canopies -- answer: bend the arms back a bit, because otherwise, it's impossible.
But our pretty new light fixtures are now installed. They don't give quite as much illumination per watt, because they're a bit more opaque than the builder-grade fixtures, but there's room for another bulb in each.
Which is a project for another day. :)