I'm lucky in that one of our local nurseries sells their potatoes individually by weight, so I usually grow two or three rows of my favourites, and then just one thirty foot row with lots of different ones, perhaps just two or three tubers to each variety. This way I can see how they grow on my soil, and if I like the taste, because taste is so subjective, and what one person loves another may not. A winner for me last year was Manitou, a red potato that far surpasses Desire in size, volume of crop and flavour. I was also impressed with Pink Gypsy. At least with only growing a few of each if you don't like them, or they don't thrive, you haven't wasted a whole row.