Preheat oven to 350 degrees F. Grease and flour bottom(s) only of one 9x5 loaf pan or three 6x3-1/2 loaf pans. Beat together sugar and oil in a large bowl. Add bananas, yogurt, vanilla, and eggs; blend well. Add flour, baking soda, and salt; stir just until dry ingredients are moistened. Gently stir in blueberries. Pour into prepared pan(s).
Bake for 60-70 minutes for single large loaf; 40-50 minutes for three small loaves. Check doneness by inserting a toothpick in the center of loaf; if clean when removed, bread is done. Cool 5 minutes in pan(s), then remove from pan(s). Cool completely. Wrap tightly and store in refrigerator.