Having a staircase near the main entrance reduces the disturbance as one can go to the upper floor right after they enter the home.

 Some times stair cases are built in the center, like in  so many movies, they probably have just one set which they keep repeating :) but I don't like the idea of stair case in the center of living room or across the living room other wise you could wake every one up when you come home after a late night party.

According to vastu, staircases should be constructed in the South, West or South-West quadrant. Never construct staircase in the North-East direction it may cause loss of wealth and business. While climbing up in the stairs it should always turn in clockwise direction. Number of steps shold be odd. Under the staircases no room should be constructed, you can use this space to store the waste material of the house.