It depends on what music the couple like and the age groups/tastes of those attending.
I would guess a few classics from the 60s, 70s, 80s, 90s and 00s. Even the 50s- the Twist is still good fun after a few drinks. A bit of Grease and Dirty Dancing. Some Take That and Abba. And have some current stuff such as Black Eyed Peas