In a large bowl toss together the cereals, melted stick of butter, vanilla and 1-2 teaspoons of the remaining cinnamon sugar from earlier. Toss well and then spread out between two cookie sheets. Bake for 15 minutes at 300°F, stirring once or twice during cooking. Remove and allow to cool. Once cool, add the cereal, snickerdoodles and pecans to a large bowl and toss well. Serve.