You could always check out Sumatra. If you're looking for off the bubbled path there's a private island called Cubadak reached from Jakarta > Padang where Marco will have you driven across the island to Corococ Port and boat transfer. There's only a few (less than ten) bungalows diving on demand - not Komodo RA or Alor standards but for beaching it, it's a lovely peaceful place. Heaps of little black tips so it appears to be a bit of a shark nursery. It's the beginning of the mentawi island chain so Indian Ocean.
Sumatra topside is fascinating - Lake Toba is worth the bumpy roads. Lots of culture.
Another option is Bangka Sulawesi not Bangka Sumatra - from Bangka there's day trips over to Lembeh and Bunaken. Topside, climb Mt Tangkoko to see Tarsiers in the wild, hornbills, cuscus and the uber cool crested macaque or Yaki...surfing monkeys with loveheartd on their bums and Mohawks will put a smile on anyone's face. There's also the highlands flower village of Tomohon quite nearby so you have quite a few topside options, Bangka, Lembeh, bunaken and mainland manado diving without too much travel time between the three - no planes needed.