I'm going to Brunei for 2 weeks in April, and hope to use it as a base for exploring Malaysian and Indonesian Borneo. It doesn't look that big on a map, but I'm aware the terrain is mountainous with thick jungle with few good roads. I've been told Kota Kinabalu in Sabah is a 6 hour car drive from Bandar Seri Begawan (Brunei).
Does anyone have any experience of travelling around Borneo, and can you give some ideas of what to do and see?

If anyone else is planning on going to Brunei from Manila, flights are not great. Only Royal Brunei and Cebu Pacific fly there. RB operate 2 flights daily (and they are not cheap), CP fly once every 2 or 3 days at something like 2 AM in the morning