I went to Indonesia last year and spent 2 days in Sumatra in Medan to see the largest crater lake in the world
Spent 2 days in Yogyakarta saw the borabadur and prambanan temple went to mt bromo and then to mt Ijen and from there to Bali .
Every thing we saw was beautiful if you need I can give you travel agent information the whole 10 day trip costs about $800 per person including car driver guide entrance fee and hotels