I asked Cary Moon—Seattle's poster woman for groovy urban planning—why she chose Nickels over Mike McGinn in the mayor's race.

McGinn's Green rap is in synch with Moon's, particularly on Moon's signature issue, building a surface/transit option instead of a tunnel along the waterfront. 

Moon says: 

I like Mike a lot, and I like Mayor Nickels too. I like Nickels better for Mayor. They both have superb intentions, but I think Nickels has the edge in being able to make things happen. And Nickel's position of being the president of US Conference of Mayors next year is a big deal to me, as he will be able to spread the good word to 850+ other mayors and (I hope) help them get the urban / environmental agenda underway across the county.

Regarding the tunnel, I had a front row seat watching how hard Nickels and Sims worked for surface / transit/ I-5. In the end, the Governor had more power and money and less courage. At the time the two choices for them were either solidarity around the tunnel, or leave it open for Frank Chopp to take the lead.