A somewhat tardy reply to Westcoaster:
By chance did you notice low long the regular check-in lines were at the time?

Actually no. I was running late, so I ran downstairs, grabbed my bags, and went straight out the front door. Didn't even look back. FWIW, on my outbound 4-1 flight at 0900, the SEA check-in area was a madhouse. I chalked that up to Spring break, as there seemed to be many whole families unsure of the check-in procedure.

cethen