Combine sugar and butter in large bowl. Beat at medium speed, scraping bowl often, until creamy. Add eggs, vanilla and orange zest; continue beating until well mixed.
Combine flour, baking powder, baking soda and salt in medium bowl. Beat at low speed, adding flour mixture alternately with sour cream and scraping bowl often, until well mixed. Divide dough into thirds; wrap in plastic food wrap. Refrigerate at least 2 hours until firm.
Heat oven to 400°F. Roll out dough on lightly floured surface, one portion at a time (keeping remaining dough refrigerated), to 1/4-inch thickness. Cut with 3-inch cookie cutters. Place 1 inch apart onto ungreased cookie sheets. Sprinkle cookies with decorator sugars or bake plain.
Bake 6-9 minutes or until edges are lightly browned.
Store these cookies in a container with a tight-fitting lid. Add a small piece of bread or an apple slice for even softer cookies.