I have adored the work of J.C. Leyendecker for about a year or so (as long as I've known of him). He was a prominent artist for the first part of the twentieth century, famous for poster work, and illustrations for the Saturday Evening Post and Arrow shirts. His brother Frank was also an illustrator, but it seems as though J.C. is the most famous.
My favorite illustration at the moment is The Butterfly Couple (1923), pictured above. I floated around the internet searching for these pictures, but apparently there's a book on the market that is going on my wish list. Enjoy!