I spent two years working in the hotel industry (four and five star hotels). And from that perspective, trying to run a party like those that have been held in the past just doesn't seem very likely.
i know that the forum party started off as more or less an informal get-together, something fun to do, and to get forumites together. It is supposed to be fairly free-flowing, spontaneous, and cheap. You go whatever time you want to go, you leave whatever time you want to leave. If you can afford to put some money into the pot, you will...if you can't, that's okay.
I'd suggest that, with the numbers we are dealing with now, we're gonna' have to change our thinking. Hotel rooms aren't gonna' cut it...and I'd suggest we should stop looking at that option. Unless we're planning on renting the Presidential Suite at the top of a hotel, and taking over the entire floor for ourselves, it just won't work.
Instead, we need to be looking at renting spaces -- convention halls, or places that cater to wedding parties, for example -- that are off the main strip. Places that we can have all to ourselves, but at fairly minimal cost. Places that tend to be busy during the day (hosting conventions, wedding parties, etc.), but not in the evening, so will be glad for the opportunity to make some extra money renting the space out, without expecting us to buy our food and drinks from them.
And we'll need to look into renting buses (which actually is not that expensive on a per-person basis), and selling tickets for everyone that comes (not hugely expensive, but enough to be sure of covering basic costs such as rental of the space, and transportation).
As mentioned above, this will no longer be a thing of just telling people a time and a place...it will take a committee of people to formally organize it, and put everything together. I know that some people will object to this...but from my perspective, it is a choice either between this, or just stopping the forum party altogether.