Hey, I don't mean to be critical, but in most states a homeowner is not allowed to to electrical work.  It requires obtaining a building permit and using a licensed electrician.  In your slide show, the first example, the small gable, doesn't meet the goal of protecting someone from the elements while waiting at the door.  In the small shed picture, since there is a storm door shown, at least one person would have to step back out into the rain to get around the door.

For people designing a new home, especially a larger one, using a 3'-6" wide x 8' tall front door gives a feeling of grandness as you enter.  It also makes moving a lot easier.