The minute money is exchanged, you have problems.

If you charge anything beyond the actual cost of the snacks, room, etc., that will look like prostitution.

Do you in fact just want to have some fun with this as opposed to earning something for yourself?

Interesting.

In any case, be very discreet and screen carefully.

(still not a lawyer)

Asking for money is asking for trouble...

If you put a group of total strangers in a hotel room, ask them each for money and one of them turns out to be a cop then you are in for problems.

I guess my question would be where are the participants coming from? Is it folks you know or are you running an ad somewhere?  A group of known consenting adults should present no problem. Total strangers would be another matter.

I imagine the problem would be similar to the  Brouhaha caused when the neighbors found a tenant in a residential area was hosting swingers parties.  They called the cops.  The  cops found the Swingers were organized through a "club" which they paid to join.  The organizers names were made public when it went to court.  I think the tenant beat the rap but costly in lawyer's fees.  The Landlord was unhappy, sure won't give a good referance.  

To do this & get away with it, one would need intercommecting rooms or suites, adequate for the number of people involved...   away from the rest of hotel patrons.  I imagine this would be quite costly.  Perhaps some sort of confrence center?  Get the hotel to provide at least some of the food...  then get them out.  

No one calls the cops if "The Donald" throws a party.  
skb