Recently returned from my first trip to Borneo. Primary motivation was diving Sipidan, but it takes so long to get there from San Francisco that we decided to visit a longhouse and try to see (and photograph some wildlife).
Started in Sarawak with a longhouse visit upriver from Batang Ai dam. Great people photography, but the 5 hour (each way) drive from Kuching was not nice - there must be some more accessable authentic longhouses (although i don't know how to find them)
Turns out we were there at the wrong time of year and month for best animal photography -- should go in June-July (when trees are fruiting) and in the dark of the moon for nocturnal animals. Saw Orang-utans at the Sepilok rehabilitatiion center (interesting, but in June-July the time would be better spent looking for them in the wild).
Rainforest lodge in Sukau provides good views into the rainforest from the river in smaller boats with 4-cycle outboards and auxilary electric motors (the lodge is not air conditioned with mediocre food, but may get some refurbishment pretty soon).
Raiforest shooting conditions - everthing is distant, in shadow, and mostly small (except for the "pygmy" elephants). I shot a 20D with 100-400 and telephoto flash - often using the flash as the primary light with ambient fill. And it wasn't long enough. I taped the pins and put on the 1.4x and got a few decent shots (slide showable, but not really printable) of proboscis monkeys from the boat with a monopod (and of course flash), but most of the time there wasn't enough light to focus with the 1.4x. A few decent bird shots at night. During the day, a reasonable number of Hornbills, but 640mm wasn't enough.
After elaborate rain precautions, the solution proved simple - put the camera under your poncho. My Warmlite poncho was superb (you can buy a plastic poncho locally for $2, but they don't drape nicely and aren't sealled on the sides. When it rains, it's so heavy there's no point in a camera cover, you're not going to take any pictures. Some dessicant and XL ziplocks are good insurance. Since we were mostly un-air-contidioned, condensation was not a bid problem, and most of the air conditioned place could be turned up to 78-80F which was good for the cameras and good for the lungs.
Had higher expectations for the Danum Valley which is a very large preserve. But this was disappointing in animal life. Ultimately saw (and got mediocre photos of) gibbons and red leaf monkeys - and one male Orang-utan during the day. Night hikes were a bust -- the animals are too far up in the canopy to see. The best night viewing was from the truck drive on the road - one or two flying sqirrels every night, a flying lemur (which isn't really a lemur and of course, glides rather than flies), and finally a brief glimpse of a slow loris. The guide's lights were not always able to provide focus light, but my 100 lumen Surefire was - it just needed another intelligent hand to illuminate the subject - need to investigate a focus light holder (number 2 on my wish list is a dedicated, rugged telephoto flash with built-in focus light. number 1 is a 100-400 that is sharp wide open and will autofocus with a 1.4x extender on a crop-frame camera).
If you're interested in anything rare, forget it - our guide had seen 3 clouded leopards in 10 years. The last rhino sighting was about 10 years ago.
Light colored clothing is easier to inspect for leaches (my wife and i each got leached once - bloody, but no itching afterwards like a mosquito bite). Leaches are worse in the rainy season, starting Oct, but fewer mosquitios - the Malarone was probably a waste of money, Borneo does not have a high incidence of malaria even in the dry season.
The diving. Visibility was poor as there wer storms a couple weeks before we arrived. So my best shot were close and macro. Enormous amount of fish life at Sipidan, but i enjoyed the muck diving around Mabul and Kapalai as much or more (if Sipidan visibility were better my opinion might be different).
Spent a couple days in Kuala Lumpur on the way back. The butterfly park was intersting, but no really exceptional subjects. The bird park was well worth a visit - if you're there - not a lot to do in K-L.