Beat butter at medium speed with an electric mixer until creamy; gradually add sugars, beating well. Add eggs, one at a time, beating just until yellow disappears after each addition. Stir in vanilla.
Combine flour and next 3 ingredients; gradually add to butter mixture, beating until blended. Stir in oats, morsels, and pecans. Drop by tablespoonfuls onto greased baking sheets.
Bake at 350° for 12 minutes. Cool on baking sheets 3 minutes; remove to wire racks to cool completely.