Would that be with or without the 1900 Hurricane?
It existed OTL, so...
The problem with the Free State, or most of these other proposals, is that they exist in states that are big enough that they can "overwhelm" the Sin City politically and make it have to operate illegally. This is basically what did Galveston in; sure,
Galveston might have been okay with all that sin going on, but Dallas? Austin? Much less Lubbock or Odessa...so it was basically something that could exist only as long as the rest of Texas wasn't bothered enough by it to clean it up. Once they decided that the Free State had to go, it went. Las Vegas, by contrast, was a big proportion of the population in its state, so it had outsized political leverage. Thus, instead of having to do everything on the down-low, vice pushers could just operate in the open.
So what you need to do to find an alternative is to find somewhere where not only can vice be the main or at least a major industry, but also which is big enough relative to the state it operates in that it dominates politics there, meaning that the vice can be legal and the pushers can operate openly. The obvious possibility that comes to mind--to me, anyway--is Honolulu, but it's probably too remote, the state's political scene too dominated by sugar and pineapple interests in the first half of the century, and the state's existing population too socially conservative for things to come together the way they did for Las Vegas. It would be amusing, though, especially since Las Vegas is the favorite mainland destination of most locals...