I feed a grain free, Nature's Variety Instinct. I don't mix flavors, only because it would be entirely too much food, even if I used only the smallest bags, to be eaten in a reasonable amount of time. I only have one dog eating that food, and I buy the 13 lb bags. It lasts him a few months, which is probably too long to have the bag open, and I need to get him a better storage container for his food. He just does well on the grain free stuff, so that's what I use for him.