I read somewhere (Woman's Day) adding instant pudding to the cookie dough and a quarter cup of oil made a softer cookie, plumper, too, so I have always done that since. Love the results. A number of the Farmer's Wife Sampler Quilt group that continued on into Pony Club on the BOM site of QB could tell you how much they loved my Chocolate Cowboy Cookies last Christmas. Flattery might even get them a repeat this year! I believe I sent five kinds of cookies out, and that one was the most popular one.
My DGM always folded in a teaspoon of baking soda and a teaspoon of vinegar into her mix just before putting the cookies or cake into the oven to make it rise faster and better.