I did a double take as I walked past gate A9 and saw Boeing Field as the destination! It was a 737-900 departing in about 20 minutes. Seat map on the gate display showed it virtually empty yet there were about a dozen people sitting at the gate for what appeared to be that flight.

Looking at FlightAware, it flew the flight on time and I see another one flew earlier in the week too. Was this being sent there for some work and they turned it into a revenue flight just because they could? Who would be flying on it? The people waiting appeared to be some couples in their 50s/60s.