Quite a lot. But that depends on where your interests are. You can visit the following places
1. Gili trawangan
2. Nusa penida
3. Nusa dua (for water sports)
4. Ubud
5. Seminiyak / kuta/ legian
There are many places in Bali. Don't miss these for sure- Tanha lot temple, Uluwatu temple and kachak dance, Padang Padang beach, Kuta, Ubud and Kintamani volcano visit, the Lake temple and there are many more.