Hi Tara, Although it may be a bit difficult to find a clear pattern, I think there are two patterns at least in your examples. 1. の can (or sometimes should) be omitted if the outcome can also be a noun or at least a well-known combination. For example, 年越しそば is a well-known word and recognized as a single noun by everyone. If the outcome is a well-known word, it's usually natural to omit の. You could also say 年越しのそば but it sounds redundant to me unless it's on purpose. I think it is similar to the difference of American foods and foods of america. As for 関東の料理, if there is a particular type of dishes for the word 関東料理 or at least some dishes that most of people would think of as a 関東料理, you could say it but as far as I know there are no such thing. So it sounds a bit weird to me. On the other hand, 関東の料理 tends to imply more vague definition such as any dishes usually seen in 関東 region. But still as it's vague, your listener may ask like what? depending on the context. 2. Just a shortened form. In this pattern, の is omitted just because it is easier to say. I think 家族皆 falls under this category. This one also depends on if the outcome is common or not. 家族みんな is definitely a common way to say. So there should be no problem. Although this is completely my personal opinion, once the pattern 2 became so common/popular, maybe enough to be on a dictionary, it would be classified into pattern 1. There may be a better academic explanation for this but these are how I see as one of the native Japanese speakers. Thanks!