Hannah – I was looking at The Harlequin which is right across the street from the Marriott Marquis, so it seems to be the most convenient option outside the hotels. I ended up not booking it only because I don’t think we’ll end up having a reception this year. So you could look into that. they also own some other bars in the area but they were further from the hotel and I usually try to book in or very close to the main hotel for the meeting.
I did not look into options in the Union Square area.