My Great Uncle sold "flooring" which in-the-day meant vinyl or carpeting. Each area of his house had something different. Vinyl in kitchen/dining room, a lovely patterned carpet in the formal living room & dining room, one bedroom wing had another carpet, family room - different carpet, and the master's suite a 4th carpet. Thresholds were interesting to say the least. But carpet everywhere was the thing to do in the 1960's and 1970's. Funny how things are coming full circle. Unless you have in-floor heating, one thing carpet does hold over solid flooring is that it's warmer. Not important in the sun belt, but does have it's value in cooler climes.