Cook potatoes in boiling salted water to cover 15 to 20 minutes or until tender; drain. Toss potatoes with green onions and 1/3 cup vinaigrette; season with salt and pepper to taste. Cover and chill 2 to 24 hours.
Peel and chop avocados; toss with lemon juice. Toss lettuce with avocado mixture, tomatoes, and next 2 ingredients. Arrange lettuce mixture on a large serving platter; top with potato mixture, and sprinkle with bacon. Serve with remaining vinaigrette.
Note: We tested with Marie's Blue Cheese Vinaigrette.