Cherating is the only real backpacker hub at the east coast of the peninsula on the mainland. Offering plenty of affordable chalets and a relaxed atmosphere, it is good place to stop for a night or two on the way up or down the east coast. The beach itself is not that spectacular and misses the palm directly at the beach. But it has a good vibe and few things you can do like taking a tour or renting a kayak up the river into the mangroves. There is also an active surfer scene when the waves are right. Cherating is located about 30km or 1h by local bus north of Kuantan.
The Gunung Mulu National Park in Borneo (near Miri) is a UNESCO World Heritage Site with caves and karst formations. The caves are home to over 5 million bats who exit the caves in search for food every evening in a spectacular way.