Gateway Theater in Wenatchee regulary offers sensory friendly (lights up, low sound, movement allowed) showings of movies for kids. Contact them for the next Showing.
Just learned about this amazing opportunity with Seattle Symphony – Sensory Friendly Concerts!
Pacific Science Center – Sensory Friendly Early Open
Low Sensory Evenings at KidsQuest Children’s Museum
Bellevue’s KidsQuest Museum continues to offer Low Sensory Evenings at its new location beginning in March 2017. On the first Wednesday of the month from 5:30 to 7:30 p.m., kids with sensory sensitivities or other special needs can visit with reduced noise and light
Here is an article that lists many things to do in Seattle, including wonderful fenced playgrounds
Call Seattle Aquarium about their Sensory Friendly Early Open times