Church halls are too open after 10 PM, it just depends who you are dealing with. Main worry for a regular Saturday night thing would be assuring them you would do your own sweep-up afterwards since the next thing in the room would be Sunday AM coffee hour. Sweeten the deal by offering to teach some stuff to the Sunday School kids or do a yearly benefit.

The Men's Chorus here, for example, has an ongoing relationship with our church. It has from time to time included rehearsal space. They also hold an annual fundraiser in our hall, for themselves. They give us an annual appearance in the main worship service, where they sing several selections along with our small choir.

You could try contacting whoever is leading contemporary praise-worship services in the area, since they would have guitar players and singers who (presumably) have a life outside the church, as musicians, too.... and see if they could help you get a relationship going.

Or try churches with big social ministries who would see folkies as leftie pals! *G*

Me, I'd hold it at a soup kitchen or shelter, and make everybody happy...

Be creative!

~S~