Preheat oven to 325 degrees. Spray a 12 cup bundt pan with nonstick cooking spray and add a few tablespoons of all-purpose flour to pan, shake it around to coat well, then tap out and discard any excess.
In the bowl of an electric stand up mixer, gradually beat butter until it's creamy. Add sugar and beat at medium speed for 5-7 minutes, or until mixture is light and fluffy. (I beat for 7 minutes). Add eggs, one at a time, beating just until the yolk disappears and is incorporated into the batter.
In a medium bowl, mix together flour, salt, and baking soda. Add to butter mixture, alternating with sour cream, beginning and ending with the flour mixture. Beat batter on low just until blended after each addition.
With the mixer on low, stir in vanilla and peaches and continue to beat for about 1 minute. Using a large rubber spatula or wooden spoon, give the batter a final stir and make sure the peaches are mixed evenly throughout the batter.
Pour the batter into prepared pan, filling the pan only 3/4 full, and bake in preheated oven for 1 hour and 20 minutes to 1 hour and 40 minutes, testing until a wooden skewer or cake tester, inserted into the center of the cake just comes out clean, without any crumbs. Cool pan on a wire rack for 10-15 minutes, then inverts the pan onto a plate, removing cake from pan and cool completely.
Meanwhile, make the glaze: add powdered sugar to a medium bowl. Add milk or cream to powdered sugar, 1 tablespoon at a time as needed, mixing well after each addition, until you reach desired, pourable consistency. Pour over completely cooled cake. Let cake sit for the glaze to set, then serve.