It occurs to me that the phrase "Happy Holidays" may have an additional meaning. As you probably know, what we in the US call a "Vacation" is called a "Holiday" on the other side of the Atlantic. Therefore, the phrase "Happy Holidays" could be used not only a one-size-fits-all season's greeting, but could also be used as a sort of "bon voyage." So, whether you're traveling this season, or staying home, happy holidays to you.