My research now concluded, I can confidently report based on observation (as well as the resigned shoulder shrugging of my colleagues in Seattle) it is indeed grey there the entire winter. Nevertheless, people have found ways to add color to the otherwise muted landscape.
The trip home was ho-hum smooth sailing. Had dinner at Anthony's at Sea-Tac, within the massive central shopping-mall-atrium-wall-audiologists-nightmare that is the Seattle Tacoma Airport's main terminal dining and shopping zone. This restaurant used to offer one of the best airport meals in the country (if you like fresh seafood), but it looks like they're slipping off a bit. You can sit at a counter that's practically in the open kitchen, which usually puts you face-to-face with the guy making the salads or frying chips. That's where I sit, and the guys didn't have their usual smart-ass spunk and hustle this time -- maybe that's why the food wasn't so good. Even the waitress was scowly.
The flight was a by-the-numbers short haul United late evening flight, with the flight attendants making it clear they just didn't care (was the end of a long day for everyone). The only thing that raised the hairs on my arms was a few times the pilot repeated the ATC instructions back wrong -- including the RUNWAY we were supposed to land on as we were on final approach into SFO. This airport has parallel runwys, and landings are always on 26 Left and 26 Right. Normally there are airplanes landing on both runways simultaneously, so if the pilot gets them mixed up, well . . .
You don't hear stuff like that too often on United's inflight audio channel 9, but it does happen. Luckily the ATC corrected the pilot and we landed safely.