The Olympia Community School is outstanding (or was when my two youngest were there) and while it goes to three, we set up a series of after school enrichment classes, so there was an opportunity to stay as late as you needed.
Also, as susanc wrote, the family support center would have a list of places.
You can also check with WA state child services. They have lists of daycare homes that have been somewhat vetted. I would always go and check out any place you are leaving your child. Visit for a couple of hours. See if it is a place you see your children thriving in—not just passing time.