After working it all out, I crocheted a hat in a smaller yarn, then another in a larger yarn. Interesting. The way I write my patterns, it works out.
Instead of crocheting to a number of stitches per row or round, I crochet to a size of diameter of opening and length of crown. With this technique, it really doesn't matter which size yarn I use!
So... this year, I am going to work it all out on my blog as a looonnnngggg tutorial.