The studies I've seen for the SeaTac proposal showed a much smaller percentage rise in the cost of the goods, compared to the percentage increase to the wage. Hopefully the impact to those not being bumped up a little (the non locals) won't be too harmful.

Thinking about it more, along with Tony's comment about the "laboratories of democracy", it is probably best to push for this at the regional level. SeaTac is a great start, in an area where demand isn't likely to change, and most of the business comes from non residents of the area. I look forward to seeing the research from SeaTac in a few years to see the outcome.