I am about to have wood floors refinished and when that takes place, I am going for the no shoes in the house rule. When that time comes, I am going to have a shoe rack at the door with a basket of cushy, funky and colorful socks if my guests want to wear them.
I am doing this because 80%, yes, 80% of dirt in a house comes directly from the bottom of shoes that are worn outdoors. Also, the grit from the shoes is what scratches the floors and gets caught under the legs of furniture which then scratch the floors when the furniture is moved over the grit. This happens whether you are a good housekeeper or not. Also, grit on the floors also makes the finish dull.
Those are the reasons why I would like to have a no shoes in house rule after my wood floors are refinished. This rule will apply to all friends and family with the exception of when I have semi formal parties. I would hate to wear no shoes with a cocktail dress, so I would not expect my guests to do so either.