I'm in Takengon. I did a short solo trip in Gunung Leuser National Park (guides apparently are not required, but should you actually want to get to any specific location as opposed to just wandering around, it might be a good idea.) The jungle was cool, but it's not my favorite--you don't get any vista-type views--it's solid jungle canopy all the time that in some sense doesn't really change. Leaches and insects and monkeys and hot springs are fun, but I prefer alpine country. So now I'm a little further north in Takengon, with one more horrible bus ride (and, ummm, GI issues) remaining between me and surfing/snorkeling in Banda Aceh.