The only city I absolutely, definitely would NOT want to do for a meetup is New York. I know it sounds cool in theory but it's a really terrible idea for the this type of meetup. Just my two cents.
AND I have to suggest Baltimore every year because:
a) It's my hometown
b) Like 6/14 meetup lambs also live there
C) It's actually a really fun, unique city. It gets a bad wrap and doesn't deserve it. And I don't want to hear anyone mention crime because we just went to Chicago where like a billion people a day are shot or killed in traffic accidents.
d) It would be a cheaper option than New York