How big is the conference? Lots of wineries have banquet facilities, especially if your numbers aren't big. East Dell in Beamsville has a lovely view and a large dining room. I don't know if they're set up for conferences, though. Vineland has a small banquet room, probably very pricey though. Those are two I can think of off the top of my head, but there are so many new wineries cropping up all the time. Call around.
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