Hi Blacky...you have got me. I always swore I would not be one of those people who would not share a recipe saying "I just throw things in". But I can't really explain these. Best I can tell you is experiment with the following
Choc Chip - I add multiple levels of choc - some semi sweet some sweet and a tiny amount of DARK. I don't just use pre-made chips, but chop pieces of my favorite chocolates. I also use salted butter and a teeny tiny more salt than the recipe says---cuts that cloying sweetness. I play with the vanilla amount too - more but I could not really say how much. Finally - I only bake them from very cold dough. These all seemed to have helped. Oh and a few drops (drops only) of brewed coffee in with some of the vanilla.
The sugar.....I use a bunch of different recipes....my biggest secrets there are use only very cold dough, don't roll too thin (I think mine are about 3/4"). I also tend to use a little more flavorings and bake until just barely browned. The biggest fav about my sugar are the oil painting icing that I do and that my buttercream is not overly sweet.