Where to have a going away party?

My wife and I are moving out of state and want to have a going away party for all our co-workers and friends! We are thinking of renting a room at a bar or something for a few hours in the early evening and then moving to the Jones for the rest of the night. No food is needed. Just drinks.

Do any bars have rooms or private spaces to rent? We anticipate between 50-75 people coming and going throughout to night. Looking for the midtown/downtown area on a Saturday.