East side is far more expensive, and so is office space, head tax notwithstanding. Does the over/under on that work out? My guess is no. Seattle has far better transit, still cheaper housing and office space.
The problem with location is that for almost all the companies I have worked for in the Seattle area, almost every single person lives on the east side (cause we are older, have families, etc and got imported here by Microsoft). New people, those young college kids, they all start in Seattle, whether at amazon or not. When I moved here years ago I wanted to be close to my work, so I was at Microsoft.