"Do you have any particular suggestions of how we can search these venues out?"
Not particularly in NYC, since I live in So. Cal. Here, we have a publication (online, too) called "Here Comes the Guide",which lists many wedding venues by area. I have doen searches on the internet, simply by naming a city or county and "Wedding Receptions," or some similar wording. Often, the websites of caterers, florists, planners, and others in the business list venues with which they are connected. Or, you could name a city or town and a type of facility (e.g. "libraries, Yonkers", or "museums, Brooklyn") and see what pops up. Word of mouth always is good, as is putting out the word to everyone you encounter (e.g. I found a great party venue through a shopkeeper that I patronize, just because she had held her daughter's wedding there--it was a small museum, by the way). So, chat up everyone and see what you find.
myra@classysassyweddings.com