a few things.
I had already looked into most of the suggestions made and there are many issues.

Aside from the fact that due to other events in Vegas the same week, hotels, restaurants etc. are likely to be running at 90%+ capacity, even at a quieter time a regular 'booking' would have been out of the question for our needs.
In the past the Palms gave us 'concessions' way beyond what you could ordinarily expect, i.e.

Reserving a whole section of a restaurant for private use for 4 hours.
Providing additional staffing with no requirement whatsoever for anyone to spend anything.
No deposit and separate checks for everyone.

It would seem that once a party size exceeds 20 then everywhere will treat it as a private event and require a payment up front which varies between $25 & $50 per person. Given that half the people don't even eat at this event this ain't going to work. Also unlikely you would have any choice over food. We already have a banquet on Wednesday, we don't need another one.
Plenty reasons why restaurants stipulate this - blocking off 100+ seats (which in most cases means the entire restaurant) and then having no-shows does not work. Extra staff are required to make sure people don't have to wait for two hours to be served as I can't predict when people will arrive.

Those I talked to in the past few months and those that emailed me directly as a result of my initial post were ALL in favor of the South Point, because...
Everyone knows where it is
Everyone has been happy with SP for all our other needs that week.
They can drink and not have to worry about driving or taxi fares

None of the restaurants or the Coronado Cafe could accomodate us anyway. I am still working on the buffet but it means everyone has to pay whatever it is to get in, and alcohol service is sloooooooowwwwwwww in there, so not sure that works anyway.

Regarding the seating area and bar near the sportsbook, there are other issues
Although people get their take-out and sit there to eat, it is clearly signed that that seating is an extension of the SB and reserved for SB punters. When busy they even have it roped off and you have to show your players card. You have to be over 21, and there are only half a dozen tables for 6 anyway. That bar, which is for all intents and purposes standing only (like the splashbar) is just about the noisiest place in the casino.
And the other adjacent seating area by the coffee/sushi only holds about 20 people.

So to clarify, in the absence of anyone else, I am looking at the bar where we have the Splashy awards (do not confuse this with the Splashbar). That bar seats up to 80 people, and given our attendees wander in and out, some only stay 20 minues, others 3 hours, I think it would suffice. Outside of weekends and late at night it is invariably empty.
I am discussing the possibility that we can order Deli or other takeout food from that bar and it will be brought to us.
If that doesnt work Im sure it is not going to kill anyone to take 5 minutes out to walk to a takeout and back. Its hardly 'too far', we have to walk the same distance to the bathrooms in the convention area.

Regardless of the final arrangements, it would still be good to start getting a count on potential attendees (and so name badges can be prepared as usual) so if you intend to be there start emailing me to let me know!!
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