Saw this on the news this morning and thought it might be of interest. It is a rating prepared by checkbook.com of Puget Sound area nurseries and garden centers that provides a rough evaluation of price versus quality versus customer service. Includes a lot of independents as well as the chains and box stores.
This is normally a subscription service, but King5 has made it available on their website until 4/15.
Here is a link that might be useful: garden center ratings