If I did a week in Bali, 4 days in Yogya, then 4 more days somewhere else on java where would you suggest? If I flew or took the train to Surabaya, is there enough to see and do to keep occupied for 3-4 days/nights? I have looked at domestic airfares in Indonesia and they are unbelievably cheap so flying between 2-3 cities is no big deal.