I've seen misinformation about "Holiday Queen" and "River Queen" for a long time, but this explanation totally clears it up. The most confusing thing is that there's Holiday Queen chips, and matchbooks/advertisements for River Queen.

To make matters worse, there's the older Holiday Inn (3740 S Las Vegas Blvd), which developed into Boardwalk, is constantly being confused with Holiday Inn/Casino (3475 S Las Vegas Blvd), just as it was at the start of this thread. Wikipedia page on Boardwalk mistakenly states that it started as Holiday Queen, linking to an erroneous article.

A couple questions:

Was the Holiday Inn (3475 S Las Vegas Blvd) open long before Holiday Casino? I have two 1972 photos showing the hotel there before the casino, but it's not clear of the hotel is open.
http://vintagelasvegas.tumblr.com/post/99409234469/
http://vintagelasvegas.tumblr.com/post/100243223629/

Do you know the actual opening date of Holiday Casino? Photo from summer '73 shows the casino built but possibly not open. The hotel looks like it's open.
http://vintagelasvegas.tumblr.com/post/134691232629/