The Sacred Valley offers very little in the way of nightlife. Most towns in the valley are packed with small Picantarias or bars which serve only Chicha, the alcoholic drink made from corn which is popular with the locals.
There are several local discotecas in The Sacred Valley, but it rare to see foreign travellers dancing the night away. It is probably best to reserve your dancing shoes for nights in Lima or Cusco where the nightlife is much more developed.