Description from the Circus Circus website:

Four Full-Size Las Vegas Casinos Open 24/7! We Don't Clown Around When it Comes to Gaming.
Sleep when you get home! Our Main Casino, West Casino, Skyrise Casino and Slots A Fun offer 100,000 square feet of gaming open 24/7 just for your amusement.

(My bolding emphasis)

Looks like they include Slots A Fun as one of the four casinos within CC. I'm sure they use all CC chips, etc. now. Used to have its own Slots A Fun chips, but no more. Also had a separate slot card program at one time, but no more. I don't know about signage on the building. Still said Slots A Fun when I was there in June.

FYI, from a regulatory standpoint, there are a number of "dual" casinos that operate under one gaming license: Bally's & Paris, Wynn & Encore, Venetian & Palazzo, Flamingo & Margaritaville & O'Shea's. And of course, many of the corporate gaming operators have multi-property players card programs too.