Preheat oven to 350 °F. Line baking sheets with Silpat baking mats or parchment paper.
In a large bowl, beat butter, sugar and brown sugar together until smooth and creamy, about 2 minutes. Beat in eggs, one at a time, until well blended. Stir in vanilla.
In a medium bowl, sift together flour, baking soda, baking powder and salt. Gradually stir into butter mixture until well blended. Add oats, chips, coconut, raisins, and walnuts, and stir until well blended.
Drop batter by heaping tablespoons or with a 1 ounce ice-cream scoop onto silpat about 2 inches apart. Press tops down with the bottom of a glass to flatten cookies evenly. Bake until golden, about 16 to 18 minutes. Cool on pan for 2 minutes.
Remove from pan, and finish cooling completely on wire rack.