I spend 14 days on Java during Ramadan. The Ramadan wasn't a problem until the end when everything was closed and transportation booked out.
My itinerary was:
Jakarta - Bandung - Pangandaran - Yogyakarta - Bromo - Surabaya
Day 1: Arriving in Jakarta
Day 2: Sightseeing in Jakarta
Day 3: Train Jakarta - Bandung (100,000 IDR)
Day 4: Sightseeing outside Bandung (see below under "what to see")
Day 5: Shuttle bus Bandung - Pangandaran (5 hours, 150,000 IDR)
Day 6: Sightseeing in Pangandaran area (Green Valley and Green Canyon)
Day 7: Chilling in Pangandaran
Day 8: Shuttle bus Pangandaran - Yogyakarta (7 hours, 160,000 IDR)
Day 9: Sightseeing in Yogyakarta and booking tours
Day 10: Tours to Borobudur and Prambanan temples (see below under "what to see")
Day 11: Relax in Yogyakarta
Day 12: Mt. Bromo tour 1. day (only driving)
Day 13: Mt. Bromo tour 2. day (see Mt. Bromo and bus to Surabaya)
Day 14: Seeing Surabaya and fly back to Jakarta
ATMs of local brand banks dispense either 1,500,000 IDR if there is a 50.000 sticker on or up to 2,500,000 if there is a 100.000 sticker. Foreign bank's ATM dispense up to 3,000,000 IDR (Citibank).
There are lots and lots of guest houses in Pangandaran, but choose one at the west end near Bamboo Cafe if you want a bit of a travel vibe. I stayed at Bamboo House for 120,000 IDR.
There are two "backpacker areas" in Yogyakarta: Prawirotaman and Sosrowijayan (close to the train station). Both are great if you want everything at your doorstep, like great cafes and restaurants, bars, tour agencies, etc.
The main sights around Bandung are Tangkuban Perahu (extinct volcano) and Ciater (hot springs) about 35 km north of the town and Kawah Putih (crater lake) and Situ Patenggang (lake) about 50 km south of town. It takes a day trip to see either the north or south sights.
I only went to see Tangkuban Perahu. As going by public transportation is complicated and time consuming, I rented a scooter (100,000 IDR from my hostel Hunny, which was a bit expensive). Getting to Tangkuban Perahu was fairly easy. Went straight towards Lembang, turned left when the road sign indicated, that was all. The entrance fee was 200,000 IDR (300,000 IDR on weekends) for a foreigner like me. The road went all the way to the crater rim, where there were lots souvenir shops, vendors, and guides, but they left me alone. There is a trail along the rim (just follow the souvenir shops), but it was closed due to "danger". There are also two hot spring lakes nearby (Kawah Upas and Kawah Domas), but the guards at each entrance informed me a local guide was necessary and they costed either 300,000 IDR (Kawah Upas) or 150,000 IDR (Kawah Domas), though they were quick to inform that I could get a discount. I had heard of travellers who only payid about 25,000 IDR or so, so I declined and didn't see the lakes (which was kind of half the reason to go there in the first place).
I took a self-drive tour with guide on scooter to Green Valley and Green Canyon (200,000-250,000 IDR). Even if you normally don't like tours, these are actually quite cool. You drive through the beautiful countryside and see other stuff you won't otherwise see if you was driving on your own.
The tours agencies have pretty much the same prices. I used Losari (jogjabromotour.com).
Tours to Borobudur Temples (with or without Prambanan) 90,000-135,000 IDR (not including various entrance fees, like 2 x 200,000 IDR temples + 30,000 IDR viewpoint).
Tours to Bromo are normally like this:
Day 1: Yogyakarta - Cemoro Lawang
Day 2: Cemoro Lawang - sunrise at Mt. Bromo or from Pananjakan - touring Bromo - Probolinggo (city) - onwards travel to either Bali or Surabaya.
Prices were from 390,000 IDR (490,000 IDR if sunrise from Pananjakan) including onward travel. The accommodation is very basic but upgrades are possible.
Many other tours are also offered (like to Dieng Plateau), but they are not often booked, so you need at least to be two people.