Agree that Borneo is worth visiting. The roundtrip flight from Miri to Mulu for Gunung Mulu National Park is reasonable. It should not be a deterrent to visit the park, which has massive caves, millions of bats that fly out at dusk, etc. There are orangutans in both Sarawak and Sabah. Enjoyed my time in Brunei. Kampong Ayer, a water village near Bandar Seri Begawan, is worth visiting; and so is the night market. Take the Sabah State Railway from Tanjung Aru (near Kota Kinabalu) to Beaufort. The southern and larger part of Borneo is Kalimantan, a part of Indonesia.