In a large bowl, dissolve yeast in water. Add milk, sugar, eggs, butter, salt and 2 1/2 cups flour. Beat until smooth. Gradually stir in enough remaining flour (3 to 3 1/2 more cups) to form a soft dough.
Turn onto a floured surface and knead until smooth and elastic, about 6-8 minutes (You can also knead with a stand mixer fitted with the dough hook). Place in a greased bowl, turning once to grease top. Cover and let rise in a warm place until doubled, about 1 hour.
Punch dough down; divide in half. Roll each half into an 18-inch x 8-inch rectangle. Combine 1/2 cup sugar and 2 Tbsp. cinnamon in a small bowl. Sprinkle evenly over dough. Roll up each rectangle from short side; pinch seam to seal. Place seam side down in two greased 9-in. x 5-in. loaf pans. Cover and let rise in a warm place until doubled, about 1 1/2 hours.
Bake at 350 degrees F for 30-35 minutes or until golden brown. Remove from pans and cool on wire racks. Brush warm loaves with additional melted butter.