I have found that adding a little molasses or corn syrup to the recipe produces a chewier cookie. I like the soft kind myself, but I can see the sense in having a chewy cookie recipe on hand to send somewhere.
I also like roasted pecans in my oatmeal cookies. My husband likes walnuts, but pecans are number one, to me. I'm fond of pecans anyway, and nothing is better than toasted, salty pecan pieces in oatmeal cookies. Yummy! I also soak my raisins before adding them to the cookies. Makes them softer in the final product. They're not nearly as difficult to chew when you soak them.