The movie really is more about Auntie Mame and her larger-than-life life. At one point, Mame says "Life is a banquet, and most poor saps are starving!" It's this line that makes AFI's 100 Movies, 100 Lines list.
I had no interest in watching this movie and only watched it because it was on the AFI list. This was another of many pleasant surprises I've discovered while doing these lists.