Girl needs help finding another girl for 3-some?

My fiance is taking me on a romantic getaway this weekend to Niagara Falls. I want to do something special for him to thank him. We always talk about including another girl when we mess around but it's never happened before. He says it's up to me to find the girl (I am the pickier one, she has to be smokin hot). I have no problem being the one to find her I just don't know how. How does one girl pick up another? How do I know if she's into that type of thing before I approach her? Or do I just start a friendly conversation and see where it leads? There's quite a few strip clubs there. Is that a good place to pick up another girl? Please help. We leave tomorrow at noon!