Prepare Pecans: Preheat oven to 350°. Toss pecans in butter. Stir together sugar and next 4 ingredients in a bowl; add pecans, tossing to coat. Spread in a single layer in a nonstick aluminum foil-lined pan. Bake 10 to 13 minutes or until lightly browned and toasted. Cool in pan on a wire rack 20 minutes; separate pecans with a fork.
Prepare Vinaigrette: Whisk together cider vinegar and next 4 ingredients. Gradually whisk in oil until well blended.
Prepare Salad: Combine spinach and next 3 ingredients in a bowl. Drizzle with desired amount of Maple-Cider Vinaigrette; toss to coat. Sprinkle with pecans. Serve salad with any remaining vinaigrette.
Note: Pecans may be made up to 1 week ahead. Store in an airtight container. Vinaigrette may be made up to 3 days ahead. Cover and chill until ready to serve.