You can stress all you want over the color of the cocktail napkins, but the mark of a truly memorable party is if your guests gotta dance. And it’s the right sound track that gets them moving. “As people arrive, play some loungey music — Rhino Records has some great compilations,” says Delphine Blue, a DJ for New York City radio station WBAI. About an hour in, when people are more relaxed, move into high-energy favorites from the time most of your guests were in their early 20s. Alex Luke, director of music programming for Apple’s iTunes, suggests studying Billboard’s top 100 hits from the years your friends graduated from college (iTunes has a free database) and cherry-picking one-hit wonders. “Songs people haven’t heard in decades get a huge response,” Luke says. Late at night, throw in some curveballs. “African music, for instance, has a reggae beat that goes with most other dance music,” Blue says. “It’s like cooking with a great, unexpected spice.”