1. A drop or 2 of CARAMEL EXTRACT to the batter will enhance the rich flavor (it's by the other extract on the baking aisle at the grocery store).
2. I only use MEXICAN VANILLA (which I buy when I travel there, or from eBay). It's pure vanilla with a deep, rich flavor ~ and is actually cheaper to buy big 8 oz. bottles from eBay than the little bottles of not-as-good real vanilla at the grocery store.
3. I use mini-morsel semi-sweet chips nearly all the time (unless a customer requests milk or dark chocolate). Since they're smaller, there's more than twice as much in the same measurement as regular chips ~ and the cookies really seem chock-full of chips then.
4. DARK BROWN SUGAR ~ I don't even buy light brown sugar any more! Dark brown sugar has a touch of molasses in it, and really makes a huge difference in the taste of your baked goods! If a recipe calls for light brown, just ignore that and use dark.