Prizes at a bachelorette party if I already have an open bar?!
GEt some novelty items (penis whistles, flavoured lube)- You can buy them in bulk packs and divide for cheaper prizes
I think prizes are still a good idea. We just had a bachelorette party for a friend, and we bought cute underwear from Forever 21 and some earrings sets. We broke up the sets so each girl got a pair of earrings just for coming to the party.
It's a nice idea to use the bride's color scheme for the wedding in the party too, like the cups and plates could be black and red, for example.
I make a nice prize ;)