It is more about the fact that compared to Gili Trawangan or even Gili Meno, Gili Nanggu is much quieter. However, in this small island, you will meet the crystal clear water and white sand beach. This is a perfect place for relaxing. You can have perfect snorkeling or diving experience in this place.
If you think that hiking Mount Rinjani is not your thing, you can consider hiking Bukit Pergasingan instead. Several great things can be found from this hill which is located in Sembalun, not far from the starting point of Mount Rinjani hike.
Gili Air might attract many tourists to spend time but you should consider visiting Gili Kedis if you really want to get away from tourism crowd. Gili Kedis has some good things which can give you unique experience after all.