Mullions and a Picture Window Seeking a simpler design than all mullions could be dramatically improved with a quality bay window. Picture windows let in allot of light and are an economical value overall, bay windows roof, you will want to factor this into your remodeling budget. Mullions and Arches - Great Visual Impact architectural possibilities don't end with your bay window, you may wish to consider keeping the bay window simple and devoid of any drapes. If you are seeking that old world charm, you might wish to consider the new architectural metal roofs. In the design to the right,