Prepare couscous as directed on package. Fluff with fork, cool. In a large mixing bowl combine chicken, basil, capers, couscous and tomatoes. Toss with olive oil, lemon peel and lemon juice. Refrigerate until serving. Remove salad from refrigerator 1/2 hour prior to serving, mix in salad greens, top with feta. Drizzle with a bit of olive oil, if desired.