Washington Kayak Club has a number of pool sessions during the week. There is one tonight at the Helene Madison pool in N. Seattle. Its a little pricey - $18 for non WKC, non ACA folks. But they are close if you are in Seattle. Juanita Pool on Friday nights is $10. I think the sessions at the Wedgewood Pool (?) have been discontinued - I believe they were put on by SRK. I miss those. $10 and on weeknights.
Beyond Seattle is the UPS pool in Tacoma - there is a link here for that info.