Have you tried contacting the Seattle Public Schools Summer Semester office? If they don't have appropriate openings for your students, they may have some suggestions for local schools or organizations that do.
http://www.seattleschools.org/area/summersemester/index.dxml
 
If the kids are interested in computers, here are some summer tech camps for kids in Seattle:
http://www.internaldrive.com/why-id/summer-day-camps-and-extended-day-camp-options-at-our-computer-camps/
 
SuperCamp also has some learning and lifeskills camps you could consider:
http://www.mysummercamps.com/camps/Detailed/24345.html
 
https://www.quantumlearningnetwork.com/landingpages/LP-SuperCampGeneral.aspx?src=mysummercamps&spec=washington
 
http://www.supercamp.com/
 
I hope this information above helps you along in your search, and that you are successful in placing all three of the kids into great academic programs this summer.