OK, so the total actually comes to $660 with taxes and other "resort fees." (Ugh.) I didn't want it to get away from us, though, so I decided to stop wringing my hands and have booked the room and paid the deposit. The date is Saturday August 6, and tentative time is starting when the dealer's room closes (probably around 7pm) until...whenever we want.
I am humbly asking for voluntary donations to help cover this rather steep room cost (my Paypal is firstname.lastname@example.org), but I don't want to set a fixed admission charge or anything that might keep people from coming who don't have the money. In any case, however, I will in appreciation give credit in the opening post here to people who have helped to cover the costs as payments come in (unless you ask to remain anonymous). I'm not much of a high roller when it comes to Vegas or travel (we're paying $50 per night for the hotel room we're actually sleeping in while we're in town), so any and all help would be appreciated.
Also, FWIW, even at $50+, this will probably end up costing less per person than most of the prices we were quoted for restaurant private rooms, and in any case I think it'll be a much more secure and relaxed venue for a prop meet-up.
The room listings for Rio suites actually mention parties as one of their ideal functions, so we should be all good in that respect. (I tried calling the hotel to confirm this, but getting bounced around from dead end voicemail to dead-end voicemail, I gave up after an hour of trying.)