Preheat the oven to 350 degrees F. Combine the flour, baking soda, and salt in a large bowl. Beat the butter and sugars together until light and fluffy on medium speed in another bowl. Beat in the eggs one at a time, then add the vanilla.
At a low speed, add the flour mixture in batches until just blended. Be careful not to overbeat or the dough will toughen. Stir in chocolate chips and your choice of stir-ins with a wooden spoon until well combined. Chill the dough 30 minutes or overnight.
Shape or scoop using an ice cream scoop into 2-inch balls spaced about 3-inches apart on baking sheets. Bake until golden brown around the edges, about 15 minutes. Let cool on baking sheets, about 3 minutes. Transfer cookies to a cooling rack and cool.