To give your home more curb appeal, it pays to choose your replacement windows carefully. Next to the style of a house (colonial, Cape Cod, ranch, modern), windows are the biggest factor in determining how your home looks to the outside world.
Most older homes date back to the days when glass only was available in small panes. So it makes sense, when updating older homes to maintain a traditional look through the use of grids and trim.
Generally, windows in the front of a house should complement the style of the home. For many people, and many home styles, that means a traditional, symmetrical design. This is particularly important in neighborhoods where existing homes set a general style or style is mandated by code. On other sides of the home, you have more freedom.