i was in kota kinabalu and sipadan on the malay side... beauitiful place. if you like to dive, sipadan is world world world class... unreal diving, you go and stay there for 3 or 5 days, all food included and mindfucking shore dives...

sepilak orang rehab center is interesting if you dig that... kota itslef isnt anything to write home about...

the food is excellent, make sure you eat malaysian greens, as theyre called, a shootlike veggie that is divine...

also great fish

a visit to a longhouse is worthwhile, several friends did it, you go and stay in someones house, culturally rich experience.

My husband and I spent 10 days around Kuching and loved it. There are also very cheap flights on airasia.com that go over to Kuala Lumpur, so you could also travel mainland Malaysia as well.
We trekked in Bako National Park for three days and loved it. It's pretty rustic but not roughing it. The cabins for rent all have single beds and it feels like camp and the food is pretty basic, but we met some great locals and travellers and loved watching the crazy proboscious monkeys.
Nights in Kuching were lazy, filled with cafes, Scrabble and beer. We also did a bunch of the local museums that were hilarious because they were so dated or odd (like the Cat Museum). We went out to the orangutang sanctuary twice and could have gone more. We lucked out one time having gone back to the visitors center only to find out so had all the orangutangs, so we got to be within 10-20 feet of the largest male and two of the mothers that still had babes in arms, it was amazing.
Give yourself time to get around if you are planning to go overland, we didn't have the money to fly, but that seems the way to go for the most part. Talk with other travellers once you arrive and if you do the big hike (Kimbalu?) make sure to leave yourself enough time to enjoy it as I met two groups that had to rush up and rush down and felt they could have used another day.

Have a blast!
*steph*
aka serious