If executives of a national trade association were to hold a meeting of this length and magnitude, it would make sense to hold it in an airport hotel. Pick a date, have everyone fly in the night before. Have the meeting the next morning, and give them the afternoon to go see the city if they’ve never been there before. Fly them home the next day - a three day affair to accomplish what they need to at that meeting.
Granted, some may not be able to get early flights. In that case, an afternoon or evening meeting might be better. However, having it at an airport hotel will cut down on how far the participants have to go to get from their hotel to the meeting. If everyone stayed at the same hotel, they wouldn’t even have to leave.