For paying guests at SMR:
About the talent night stuff: meeting rooms around here (where you will find pianos) are subject to room rental charges, which could range up to $50 per hour [!]. Music stands cost $10 per day for rental. Other equipment such as microphones are available, also for a rental fee-$10 for rental, microphone stand= another $10. (PA system $60-$100). So it sounds like rental of these items is not a “Kinney” kind of expenditure(in other words, not cheap). The only available piano is in the lobby at the largest guest lodge, about a half mile from the reunion cabins; reserving it ahead is probably not possible.
There are, however, lots of room for activities in the reunion cabins. Seating at meals at tables for 40+ and seating in a living room for about the same number with a kind of upstairs bigger than balcony-size space + more comfortable seating. A group could play up there and be heard at dinner downstairs or perform there after dinner where some could listen in person and others could listen from downstairs or everyone could gather around with some sitting on couches and some at tables listening from the dining room.