Thinking of going to Indonesia in a couple of months for a holiday. Current plan is some trek to see Orangutans, Mt. Bromo and Bali. All in all, around 12 days perhaps.
I'm responsible for researching Mt. Bromo stuff. Thought i'd see if anyone on here has been before, and if so, recommendations for places to stay/see/do etc.?
Also, any other places we should be considering and are worth a visit? Any opinions on the Jogjakarta ruins would be appreciated. Seems like they might be similar to Angkor Wat? Haven't been there, but went to My Son ruins in Vietnam a couple of years ago, which are similar to Angkor Wat so not sure if Jogjakarta would be new or the same stuff.
I've been to Mt Bromo twice, once when it was erupting (well, ash pouring out of it) and second when it had stopped and I could walk up to the creator mouth and take a look down (it was still burping a bit of ash at the time). To say the least, it was awesome. You do need to be up at something like 4am to make the walk up to the best viewing point though. As someone else said, if you do go to the creator too, get a jeep (or horse) as it is some walk just to the start of the climb (which is hard going as it's all ash - or at least it was when I went).
First trip, that ash cloud was raining down on the viliage I was staying in:

Six months later, peering into the volcano from the above pic:
Both times I just booked a local 'tour' drive from Yogya to Bromo, then onto the port for the crossing over to Bali. It included an overnight stay at some place in a small village closest to Bromo so you could get up for sunrise view of Bromo. I couldn't tell you the name of the places I stayed, I was just backpacking around so it would have been cheap. I wish I could remember the first place though, as it had a lovely little inner courtyard area (covered in ash) and the rooms were pretty good. But it was bloody cold. Sorry... guess that wasn't much help
The two places I visited from Yogya were Prambanan and Borobudur (also went for a walk on Mt Merapi, lava still flowing). Borobudur is a single massive structure you walk around and climb to the top. Unlike places like Angkor Wat and My Son, it's all been tided up and re-built where it was crumbling, but all very well done - you can't really tell. I enjoyed it, got some good views etc, but it can be bloody hot while you're on the temple.
Prambanan is a little more like Angkor Wat in terms of sprawling temples (on a comparably tiny scale), but again, they've all been much more tidied up and again in much better condition than My Son etc - again I would recommend a visit, but then I like that sort of thing
As for Oran-utans, I went to the northern tip of Sumatra. Stayed in a tiny village called Bukit Lewang right on a river which was on the edge of the jungle. I basically flew into Medan (a craphole capital of Sumatra) and got a public bus straight out and up to Bukit Lewang (2-3 hours I think). Then just wandered up the road until I found a guest house with space. There are some really nice places down there and exceptionally cheap (this was in 2011) and friendly. Think I paid equivalent of 1 pound a night. Then in the morning you can just cross the bridge at the north of the village into the jungle for the morning Oran-utan feeding. You can also do longer 2/3 day jungle hikes which I would have loved to do but my visa was expiring

You can just book these with your accommodation when you arrive, but guessing with your time restrictions you might want to do something in advance.
Bali is very nice, but as someone said, avoid Kuta at all costs, it's aimed at Australian 18-25 year olds, if you get my drift. They've also ruined what was a very nice beach view by building a massive 12 foot wall between it and the sea front road (so all the restaurants that did have beach and sea views now have wall views) after the Tsunami. Ubud in the centre is often seen as cultural Bali - although it's getting majorly touristy now - it still a nice place to relax for a bit, and I did an awesome guided mountain bike ride around the surrounding areas (all down hill as they drive you to the top of the mountain first).
Lovina on the north of the island is a good place to stay too, far less touristy (and volcanic black beaches) with some awesome diving to be had.
If you're open to not actually staying the whole time in Bali then there are also a few smaller islands off the east coast which you might consider. I stayed on Nusa Lembongan. There is nothing to do there really, except eat drink and relax. Or you might consider getting off Bali and over to Lombok and a small town on the west coast called Senggigi. I didn't get to Gilli Air, but heard very good things. I'd recommend looking into all of these to see what kind of stay you're looking for.
Sorry, I think this post turned out to be a bit more of a reminice for me than help for you!! I have no idea how you're going to manage just 12 days, I spent 2 months backpacking around Indonesia and I was knackered

Either way, you'll love it, the food is fantastic and the people a genuinely friendly and kind.