Preheat oven to 350°F. Grease and flour two large (9 by 5-inch) loaf pans.
In a large bowl, whisk together the flour, baking soda, salt, and pumpkin pie spice. In another large bowl, use a mixer to blend together the pumpkin puree, sugar, oil, water, eggs, and vanilla until well incorporated. Slowly add in the flour mixture, stirring until just blended.
In a small bowl, stir together the sugar and cinnamon until well combined.
Divide three-quarters of the batter between the prepared pans. Sprinkle with about three-quarters of the cinnamon sugar, and use a butter knife to swirl through each loaf. Dividing the remaining batter between the pans, and sprinkle with the remaining cinnamon sugar mixture.
Bake for 60 to 65 minutes, or until a toothpick inserted in the center comes out clean. Cool bread in pans for 5 to 10 minutes and then carefully turn out onto a wire rack to cool completely.
Loaf pans and muffin pans come in a variety of sizes, so the size of your pans will dictate how many loaves/muffins you get. Below are approximate baking times for different dimensions of pans. A toothpick inserted in the center should come out just clean, but be careful not to overbake. It's normal for the exterior of this bread to darken while the inside stays soft and moist.
Two 9 by 5-inch loaf pans >>> 60 minutes
Three 7 by 3-inch loaf pans >>> 50 minutes
Six mini loaf pans >>> 40 minutes
Approximately 3 dozen regular muffins >>> 20 to 22 minutes
Approximately 100 mini muffins >>> 12 to 14 minutes
If you're just eyeballing the size of your bread pans, I recommend putting a baking sheet under your pans in the oven just in case there's overflow.