On Saturday morning I tried c1apton's suggestion of adding a bottle of injector-cleaner treatment to the fuel. Being cold for about 15 hours, it took about 20 - 25 seconds of cranking to start the car.
I ran some errands, driving about 50 miles total (1/8 tank). Saturday night, the car was cold for about 15 hours again - but when I tried to start her Sunday morning . . . behold, she started after maybe five seconds of cranking! There SEEMS to be a major difference.
I gotta go to Seattle this week, leaving the car parked at my apartment for five days. The big test will be next Saturday morning - will she start? If the cranking time continues to decrease, then it was the injectors and c1apton's idea worked. But since the cranking time has been proportional to the time since last start, I'm keeping my fingers crossed for Saturday morning.