Having had a connection to the owner of the Win Cards Program, today I emailed him and asked a couple of questions. I am trying to get him to share some of his knowledge with us in an article for the magazine.
Here is part of his reply:
"WIN CARDS can be found at the Excalibur and Aladdin casinos, adjacent to your collector's show, at the Trop.

In addition, in Las Vegas, they are available at Circus Circus, the Four Queens, the Lady Luck, Santa Fe and Sunset Stations."