Cook bacon in a large skillet until crisp; remove bacon, reserving drippings in skillet. Crumble bacon, and set aside. Cook bread cubes in drippings over medium-high heat, stirring constantly, until crisp. Remove croutons from skillet, using a slotted spoon; drain on paper towels, and set aside.
Arrange spinach, radicchio, and green onions evenly on 6 individual salad plates. Cut goat cheese into 12 slices; cut into decorative shapes, if desired. Top each salad with 2 slices goat cheese.
Combine vinegar and remaining ingredients in a small jar; cover tightly, and shake vigorously to blend. Pour vinegar mixture evenly over salads; top evenly with reserved bacon and croutons.