Keep the party built around your music, so that people will dance, not sit about as if they'd gone to another dinner party and talk all night.
To make the room fun for dancing, I move out all the furniture and set up cabaret tables -- maybe skirted in red felt to the floor -- at the end of the room away from the orchestra. These little round tables are only 24 inches across but with small gold ballroom chairs can easily seat four. This helps to create the illusion of a night-club with tables near the dance flooor and makes a good place for people to sit briefly to watch the dancing and to change partners.
Remember that the room will be in shadow and filled with music and whirling dancers. Simple decorations will usually be enough. For Tish Baldrige's party, for example, I decorated the mantelpiece and inside the fire-place with flowering cherry, dogwood and spring flowers. Candles are tempting to put everywhere but you must be sure when they are lighted that flying hair or skirts won't be close enough to sweep into the flame and catch fire.
Placement of the bars is most important because that is where your guests will congregate. If there is a good room for overflow, in our case the library, you must put a bar there. But don't put the bar so far away from the music that people can't hear the music any longer.
Probably not too many houses are large enough to have this problem but I mention it anyway on general principles.