The Kentlands Clubhouse is one of the best venues we have used, but does cost $50/hr plus an $85 cleaning fee. Schitt generously picked up the total fees of $285 for four hours last time.
The smaller venue Kentlands Carriage House is the only free facility that is available for use around here that I know of. It is air conditioned, has decent WiFi, a private restroom, small kitchen, easy free parking, close to I-270, can host 25+ people, more if not everyone shows up at the same time as was the case for the last event we held there.
The feedback on using the Carriage House last time was that is a bit tight for the number of attendees we had and can expect. The close quarters means that background noise/conversation tends to be more intrusive when doing critical listening.