Bachelorette Party on LI

I'm a BM for one of the brides on here and we're trying to plan her Bachelorette Party on LI. Her MOH and sister will be 18 so we can't go anywhere that requires you to be 21 to enter. We thought about doing a spa day but the majority of the girls aren't into it. Right now we're thinking the day at the beach (it is in June) and then a Mexican restaurant and then some clubs. Do you have any suggestions? Preferably a place that isn't too cheesy! Thanks!