Some of those churches have wonderful acoustics. A concert hall, auditorium for plays/speakers/seminars would be great. Imagine Richard Dawkins speaking in one of these converted churches without (much) need for a microphone. Or just a place for a great band to play.
I have studied the Bible and the theology behind Christianity for many years. I have been to many churches. I have walked the depth and the breadth of the religion and, as a result of this, I have a lot of bullshit to scrape off the bottom of my shoes. ~Ziploc Surprise