Preheat the oven to 350°F. Lightly grease two large (5 x 9 inch) loaf pans with cooking spray and set aside.
In a large bowl, cream butter, 2 cups sugar, 2 teaspoons cinnamon, and salt until fluffy. Add eggs and mix well. Then add sour cream and vanilla and mix well.
Mix the remaining 3 tablespoons of sugar and 1½ teaspoons of cinnamon in a bowl and sprinkle over the batter in each loaf pan.
Tent pans with foil and bake for 40-45 minutes (or until a toothpick inserted into the middle comes out clean). Let cool before removing from pan and slicing.