Americans usually like to have advance notice when people come to see them. Only very close friends drop by unannounced. This is especially true if the guests want to stay for a few days. Here's a good rule of thumb for house guests: Short stays are best. As one 19th-century French writer put it, "The first day a man is a guest, the second a burden, the third a pest." Even relatives usually don't stay for several weeks at a time. While you're staying with an American family, try to keep your living area neat and tidy. Your host family will appreciate your consideration. And they may even invite you back!