Updated for Summer 2013 Here’s a rundown of Seattle’s free museums. I’ve included my opinion on the ages that will get the most out of the experience. Every Friday Free Seattle Museum: Soundbridge at Benaroya Hall. 200 University St.,  Seattle; 206-336-6600. Pay-what-you-can every Friday from 10-4. Suggested donation $5-15/family. Best for children under age 6. First Thursday Free Seattle Museums: Burke Museum of Natural History and Culture. Free. 10 a.m.-8 p.m., University of Washington, NE 45th Street and 17th Avenue NE; 206-543-5590. Best for kids age 3 and up. Henry Art Gallery. “Pay as you wish” (or free) 11 a.m.-9 p.m. First Thursday, University of Washington, NE 45th Street and 17th Avenue NE.…