I visited several regions of Indonesia during my 1 month trip this august, and eventhough it wasn't perfect, this was the best trip I've ever had!
Itinerary: Jakarta-Malang-East Java-Lombok-Manado-Luwuk-Banggai Islands-Luwuk-Jakarta
Price was around 75-100$ a day including accomodation, food and organized activities (which really pumps up the price because we took private tours in East Java, Mt Rinjani and excursions provided by the hostel in Banggai Laut)
Jakarta: Nice city, there are some cool monuments and museums, but there isn't really much else outside the massive malls.
Tumpak Sewu: Most popular waterfall in Java, extremely beatiful and pretty empty taking into account schools were still open and we went on a saturday. Be aware of the slippery steps tho!
Mt Bromo: We did an alternate route by going to the crater during sunrise and I honestly think it was a much better choice! The sunrise was still beatiful, you get to see the lava inside the crater and you avoid the massive crowds.
Mt Ijen: Beatiful place, but overwhelming massification of tourists. It's still a must see in Java, as the lake is awesome and you can see and chat to the workers about their work. Kind of depressing to see how exploited the workers are.
Lombok: Senaru is peaceful and the view from most accomodations is shocking. Sendang Gile waterfall is beatiful and almost empty if you visit during the late afternoon. We hiked Mt Rinjani and social media isn't lying, it's pretty demanding. Avoid going if you struggle with heights.
Manado and Bunaken: Manado and Sulawesi in general really impressed me. The people here made me understand why some people call Indonesia "The land of the smiling people". Not a single bad expereince, everyone was extremely welcoming and they even invited me to their house! On top of that, Bunaken might be one of the most unique places I've ever snokeled. I saw +30 sea turtles and the snorkling areas are almost empty. Manado as a city doesn't really have much to offer but Tomohon is really cool and the waterfalls around it are impressive.
Banggai (Peleng, Banggai Laut and Mbuang Mbuang): This was my favourite are of Indonesia by far. Ferry from Luwuk can be somewhat uncomfortable but it's worth it. Peleng has a lot to offer and the beaches are beatiful. Banggai Laut is a little bit more quiet and eventhough the beaches are polluted, the snorkel is decent and it's a nice experience anyway. You can take a boat towards Mbuang Mbuang to see the stingless jellyfish lake (which made me feel like I was in an avatar movie) and sleep in the town.
When we headed back, our ferry's motor broke down and it slowly approached the beach, putting it at risk of capsizing. Luckily help arrived before anything happened and some locals of Palau Melilis, where we had to leave our ferry, took us to a small government building, some villagers provided us with a free meal and helped us get to Banggai Laut. Definitely the craziest (and best) day of our trip.