Curate Music Broadly Until Midnight

Play for the room you have, then play for yourselves. Before midnight, keep the music broad enough that a mixed-age crowd stays on the floor: recognisable hits and dependable dance tracks rather than the deep cuts you actually listen to. Build separate playlists for cocktail hour, dinner, and dancing, since each has a different job, then let the night narrow gradually as the room does. Once most older guests have gone, the floor is yours and progressive house or whatever else you are into will land with the people still on it. Give your DJ or band an explicit must-play list and a do-not-play list, because the second one prevents more damage than the first does good.