Having a master bedroom on the 1st floor doesn’t mean you’re condemned to the 1st floor.
You could have a three story house but choose to have a master suite on the first floor simply for convenience. It all depends on what you want. Ask yourself where you’re going to be in twenty years…. Will you be able to climb stairs? Probably. Will you really want to? Probably not! Master bedrooms on the first floor, and other universal design elements, mold a home to serve its homeowner at all stages of his or her life.
First floor master bedrooms also allow the master(s) of the house to be separated from those who are dwelling on the upper floors. Perhaps you’d rather have your less than quiet teenager reside in a far off third floor bedroom while you enjoy a peaceful day of reading and snoozing in your sun-drenched 1st floor master sanctuary. Also consider the climate that will surround your home. If you’re living in the South or Southwest and you know the weather can get very hot, a 1st floor master suite might just shield you from rising hot air that normally attacks the upper levels of your house.