Alaska Airlines - N323AS
I had seen this plane come in earlier. Now it departs as Alaska 471 to Seattle.
This is a 2004-vintage Boeing 737-900, and the lack of an extra emergency exit 3/4ths of the way toward the rear shows that this is an early, non-ER version of the -900.
Alaska and Continental were the only two North American customers of the non-ER -900. Alaska did not acquire the -900ER, while Continental did (and now that Continental is merged into United, the -900ER is becoming the new workhorse of United).
N323AS, Boeing 737-900