I travelled to Borneo and Langkawi on 2005. Both places were amazing!
I spent 4 nights in Borneo and 10 nights in Langkawi.
In Borneo we stayed in the Shangri La Tanjung Aru. 4 nights was perfect as we saw the orangutans at the Shangri La Rasa Ria orphanage. That was really good! The time difference (+8 hours) really takes a few days to adjust to so we decided not to visit Sandakan as this would take a day out of our stay.
In Langkawi we stayed at the Pelangi Beach Hotel in a sea view room. This hotel was also lovely! You could walk out of the hotel into the resort and the restaurants were delicious and very cheap! There is a boat tour you can do which goes around the whole island. This is a must as you see the fish farm, caves that you wouldn't realise were there!
Langkawi is tax free so the shopping mall is a great day out!
All the locals in Malaysia are very friendly. I would definitely recommend it!