I appreciate that many Kodachrome advocates preferred K-25 because of the very fine grain. I recently started shooting Kodachrome (K-64 and expired K-200) for the first time because of the way colour is reproduced. Typically, I prefer high grain. There's a sense of aesthetic roughness and imperfection that appeals to me. By contrast, shooting with K-64 feels for me like K-25 and Velvia 50 must for other photographers. I have three rolls of PKR64 120 in the freezer, and should there ever be one last chance to have them processed, then they will be shot immediately on a project or two which are candidates for what I'd use it for. Just in case.
But again, I'm after the colour reproduction and its longevity of storage. I can get fine grain in other films, but I've yet to find another stock that approaches the way the colours are rendered.
Also, here in Toronto, I'm taking my rolls to Shoppers Drug Mart. They don't sell Kodachrome. They do, however, accept it. If I understand correctly, it is sent to Fuji labs, then to Kodak, then to Dwayne's.