Heat broiler. Arrange bread on baking sheet lined with aluminum foil. Toast 4-6 inches from heat, turning once, until light golden. Tear into large pieces and drop into mixing bowl. Place half the bread in large salad bowl. Scatter half the cucumbers, peppers, and chives, then half the onions and olives over bread.
Combine 1/4 cup oil, both vinegars, tomaotes, capers, garlic, salt, and pepper and spoon half over salad. Repeat layers with remaining ingredients. Stir once or twice but do not combine thoroughly. If bread seems dry, add oil. Refrigerate covered 1 hour to allow flavors to blend.
About 20 minutes before serving, let panzanella warm to room temperature. Taste and adjust seasonings. Garnish salad with basil and serve with cruets of oil and vinegar.