Around our way, Costco uses Fuji colour photographic paper to print from digital files. If I want a 16x20, it costs the unbelievably low amount of $8.99 to get one done there. The quality seems good, the service is incredibly fast, and there usually is someone knowledgeable to talk to. They are also happy to re-do prints that are unsatisfactory.
They also provide colour profiles for their printers for those who prefer to work in a fully colour managed system. And you can elect to have work done without any colour correction.
They bought new machines for all of their local sites a couple of years ago, and seem to be doing a lot of business.