In a large bowl, dissolve yeast in warm water. Add the sugar, salt, oil and 3 cups flour. Beat until smooth. Stir in enough remaining flour to form a soft dough.
Turn onto a floured surface; knead until smooth and elastic, about 8-10 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1-1/2 hours.
Punch dough down. Turn onto a lightly floured surface; divide dough in half. Shape each into a loaf. Place in two greased 9-in. x 5-in. loaf pans. Brush top of dough with butter Cover and let rise until doubled, about 30-45 minutes.
for optional cinnamon bread
roll dough for 1 load into 9" x 9" square. Brush surface with butter. Evenly distribute sugar and cinnamon on top. Roll tightly, then place in buttered loaf pan. Brush top of dough with butter.
Bake at 375° for 30-35 minutes or until golden brown and bread sounds hollow when tapped. Remove from pans to wire racks to cool. Yield: 2 loaves (16 slices each).