Earth NYC or 49 Grove?
I went to dinner at Earth NYC - I dont' remember it having dancing though. Food was good, timing of it all was so off - the waiter was horrible, but the manager was great and comped our entire dinner. So I give it a so-so.
I have also been to 49 Grove for drinks and dancing, I think this would be a better bachelorette spot. Not sure about food though, but this place seems to have had a fussy door. Perhaps not if you have reservations.
If you eat a late dinner, I think Buddakan and Lotus (both in Meatpacking) turn their restaurants into clubs after dinner. These might be some good options to consider.
I've been to both but not for dinner only drinks and dancing. It really depends on what you are looking for. Earth is a big draw for the Indian crowd and has some interesting drinks. 49 Grove can get really crowded and the drinks just ok. I would do dinner somewhere else in both cases...