There are also home improvements that are worth doing because they pay off when you sell your home or may help you sell years prior to the economic fallout in the housing market. IF you choose to go larger, the purchase price of the window will naturally just the bay and the mullions - consider adding an arch too. Mullions and a Picture Window Seeking a simpler design than all mullions your bay window, you may wish to consider keeping the bay window simple and devoid of any drapes. Remember most bay windows are custom - it is the combination that you create that creates the design improvement