There are Several Ways to Get to Walla Walla
One way is to fly direct to Walla Walla (ALW) from Seattle (SEA). There are only a few flights a day so check that the connections work for you.
Another way is to fly into Pasco, WA (PSC) and rent a car and drive to Walla Walla in 45 minutes.
Yet another way is to fly into Portland, OR (PDX), rent a car and drive about four hours. It is a beautiful drive along the majestic Columbia River.
Or you could rent a car at Seattle Airport and drive to Walla Walla in about five hours on the north side of the Columbia River.