The bachelorette party -- more than any other night out you've had with the girls -- is THE time to rip it up together. So go for it! Dance, drink, laugh and celebrate the bride-to-be. Just know when to cut yourself off. No one wants to play baby-sitter for the sloppy drunk girl.
Also, take your cues from the bride. If her idea of a good time is a five-star brunch, wine- tasting and then home in bed by 9:30, honor that vision. Or if she's more the dancing-on-tables-until-closing-time type -- rage it up. Whatever tone the event takes, don't fight the vibe the bride is after. Have fun and enjoy the party!