Senggigi is the most upbeat and populated area of the island and while still relatively low key when compared to Bali, you can find a number of late-night venues with live music until the early hours and free flowing drinks. Amongst these venues, two worth checking out are the Papaya and Sugar Café.
Mataram is fairly quiet and at night there are a few coffee shops and restaurants open till late, the upside being that most of these venues are free to enter. The Marina Pub is probably the most frequented bar around this area, a good place to meet locals and dance along to the live band. Besides drinking and dining, cultural shows are often put on in the resorts. In this environment you can sit back enjoy the buffet and experience some of Indonesia's ancient and unique forms of dance and performance, a highlight being the intricately designed traditional costumes.
In recent years the Gili islands have emerged as party locations, where local DJ's spin until the early hours on the beaches.