In a small mixing bowl, dissolve yeast and sugar in the warm water. Let stand until creamy, about 10 minutes.
Combine buttermilk, butter, honey and the yeast mixture in a large mixing bowl. Add salt and two cups of the flour. Whisk well to combine. Add the remaining flour, 1/2 cup at a time, mixing well with a wooden spoon after each addition. When the dough has pulled together, turn it out onto a lightly floured surface and knead until smooth and supple, about 6 minutes.
Lightly oil a large mixing bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and put in a warm place to rise until doubled in volume, about 1 hour.
Preheat oven to 375 degrees F (190 degrees F).
Deflate the dough and turn it out onto a lightly floured surface. Divide the dough into two equal pieces and form into loaves. Place the loaves into two lightly greased 9x5 inch loaf pans. Cover with a damp cloth and let rise until doubled in volume, about 40 minutes.
Bake at 375 degrees F (190 degrees C) for about 30 minutes or until the tops are golden and the bottoms of the loaves sound hollow when tapped.