1. Combine first 6 ingredients in a large, heavy-duty zip-top plastic bag. Add chicken and seal bag, turning to coat. Refrigerate at least 4 hours.
2. Preheat grill to medium-high (350° to 400°). Remove chicken from marinade, discarding marinade. Grill, on greased grill rack, 6 minutes on each side or until cooked through. Let chicken cool slightly before cutting into thin slices.
3. Toss salad greens with 1/4 cup Feta Dressing, and divide among 4 salad plates. Place chicken slices on greens, and top with feta cheese and toasted pine nuts. Serve with flatbread crackers and remaining dressing.