The Cameron Highlands (I really like their website) are the highest place in mainland Malaysia, so are also the coolest. Because of the cooler climate they grow a wide variety of fruit and veg (many strawberry's) in the Highlands. They also have vast tea plantations that are spread over some very steep hills (erm... mountains).
I must admit I had been surprised by the coolness of Malaysia before visiting the Highlands. I knew we had (purposely) picked one of the coolest times of year but I had still expected things to be hotter - but the Cameron Highlands were still a welcome break.
Whilst in the Highlands we visited the Boh Teh plantation, went to a butterfly farm and saw some giant bugs (and butterflies), had a cream tea at an English style pub, ate some tasty Indian meals, and went to stand on the peak Gunung Brinchang - the highest place in Malaysia that's accessible by road.