Just girls in the family bachlorette party?

my sister is gettin married in june and I wanted to have a little "in the family" bacholorette party with me her and my other two sisters and mom. I wasn't sure whether to go to a spa for a day? that would be kind of expensive-well all the ones i have checked have been. would there be a nice place to go do? like stone harbor new jersey? deep creek? do you know of any little getaways we could go to just to go with all us in the family. i wanted to have a party with just girls before her bachlorette party with all her friends!