Tolt hill road out of carnation is pretty good. of course, anyone that is looking for hillclimbs for fun is twisted; i prefer the hill descents for the thrills.
doing 50MPH on a bicycle is much more thrilling than doing 7 mph up some steep, arduous ascent.
For speed on descents in the city, Innes Arden Way up by Shoreline CC, and 9th/Shoreline Park out in West Seattle are both 50 MPH hills.